9.8: Graph Quadratic Functions Using Transformations (2024)

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    Learning Objectives

    By the end of this section, you will be able to:

    • • Graph quadratic equations of the form f(x)=x2+kf(x)=x2+k
    • • Graph quadratic functions of the form f(x)=(x-h)2f(x)=(x-h)2
    • Graph quadratic functions of the form f(x)=ax2f(x)=ax2
    • Graph quadratic functions using transformations
    • Find a quadratic function from its graph
    Be Prepared 9.19

    Before you get started, take this readiness quiz.

    Graph the function f(x)=x2f(x)=x2 by plotting points.
    If you missed this problem, review Example 3.54.

    Be Prepared 9.20

    Factor completely: y214y+49.y214y+49.
    If you missed this problem, review Example 6.24.

    Be Prepared 9.21

    Factor completely: 2x216x+32.2x216x+32.
    If you missed this problem, review Example 6.26.

    Graph Quadratic Functions of the form f(x)=x2+kf(x)=x2+k

    In the last section, we learned how to graph quadratic functions using their properties. Another method involves starting with the basic graph of f(x)=x2f(x)=x2 and ‘moving’ it according to information given in the function equation. We call this graphing quadratic functions using transformations.

    In the first example, we will graph the quadratic function f(x)=x2f(x)=x2 by plotting points. Then we will see what effect adding a constant, k, to the equation will have on the graph of the new function f(x)=x2+k.f(x)=x2+k.

    Example 9.53

    Graph f(x)=x2,g(x)=x2+2,f(x)=x2,g(x)=x2+2, and h(x)=x22h(x)=x22 on the same rectangular coordinate system. Describe what effect adding a constant to the function has on the basic parabola.

    Answer

    Plotting points will help us see the effect of the constants on the basic f(x)=x2f(x)=x2 graph. We fill in the chart for all three functions.

    9.8: Graph Quadratic Functions Using Transformations (2)

    The g(x) values are two more than the f(x) values. Also, the h(x) values are two less than the f(x) values. Now we will graph all three functions on the same rectangular coordinate system.

    9.8: Graph Quadratic Functions Using Transformations (3)

    The graph of g(x)=x2+2g(x)=x2+2 is the same as the graph of f(x)=x2f(x)=x2 but shifted up 2 units.

    The graph of h(x)=x22h(x)=x22 is the same as the graph of f(x)=x2f(x)=x2 but shifted down 2 units.

    Try It 9.105

    Graph f(x)=x2,g(x)=x2+1,f(x)=x2,g(x)=x2+1, and h(x)=x21h(x)=x21 on the same rectangular coordinate system.
    Describe what effect adding a constant to the function has on the basic parabola.

    Try It 9.106

    Graph f(x)=x2,g(x)=x2+6,f(x)=x2,g(x)=x2+6, and h(x)=x26h(x)=x26 on the same rectangular coordinate system.
    Describe what effect adding a constant to the function has on the basic parabola.

    The last example shows us that to graph a quadratic function of the form f(x)=x2+k,f(x)=x2+k, we take the basic parabola graph of f(x)=x2f(x)=x2 and vertically shift it up (k>0)(k>0) or shift it down (k<0)(k<0).

    This transformation is called a vertical shift.

    Graph a Quadratic Function of the form f ( x ) = x 2 + k f ( x ) = x 2 + k Using a Vertical Shift

    The graph of f(x)=x2+kf(x)=x2+k shifts the graph of f(x)=x2f(x)=x2 vertically k units.

    • If k > 0, shift the parabola vertically up k units.
    • If k < 0, shift the parabola vertically down |k||k| units.

    Now that we have seen the effect of the constant, k, it is easy to graph functions of the form f(x)=x2+k.f(x)=x2+k. We just start with the basic parabola of f(x)=x2f(x)=x2 and then shift it up or down.

    It may be helpful to practice sketching f(x)=x2f(x)=x2 quickly. We know the values and can sketch the graph from there.

    9.8: Graph Quadratic Functions Using Transformations (4)

    Once we know this parabola, it will be easy to apply the transformations. The next example will require a vertical shift.

    Example 9.54

    Graph f(x)=x23f(x)=x23 using a vertical shift.

    Answer
    We first draw the graph of f(x)=x2f(x)=x2 on
    the grid.
    9.8: Graph Quadratic Functions Using Transformations (5)
    Determine kk. 9.8: Graph Quadratic Functions Using Transformations (6)
    9.8: Graph Quadratic Functions Using Transformations (7)
    Shift the graph f(x)=x2f(x)=x2 down 3. 9.8: Graph Quadratic Functions Using Transformations (8)
    Try It 9.107

    Graph f(x)=x25f(x)=x25 using a vertical shift.

    Try It 9.108

    Graph f(x)=x2+7f(x)=x2+7 using a vertical shift.

    Graph Quadratic Functions of the form f(x)=(xh)2f(x)=(xh)2

    In the first example, we graphed the quadratic function f(x)=x2f(x)=x2 by plotting points and then saw the effect of adding a constant k to the function had on the resulting graph of the new function f(x)=x2+k.f(x)=x2+k.

    We will now explore the effect of subtracting a constant, h, from x has on the resulting graph of the new function f(x)=(xh)2.f(x)=(xh)2.

    Example 9.55

    Graph f(x)=x2,g(x)=(x1)2,f(x)=x2,g(x)=(x1)2, and h(x)=(x+1)2h(x)=(x+1)2 on the same rectangular coordinate system. Describe what effect adding a constant to the function has on the basic parabola.

    Answer

    Plotting points will help us see the effect of the constants on the basic f(x)=x2f(x)=x2 graph. We fill in the chart for all three functions.

    9.8: Graph Quadratic Functions Using Transformations (9)

    The g(x) values and the h(x) values share the common numbers 0, 1, 4, 9, and 16, but are shifted.

    9.8: Graph Quadratic Functions Using Transformations (10) 9.8: Graph Quadratic Functions Using Transformations (11)
    Try It 9.109

    Graph f(x)=x2,g(x)=(x+2)2,f(x)=x2,g(x)=(x+2)2, and h(x)=(x2)2h(x)=(x2)2 on the same rectangular coordinate system.
    Describe what effect adding a constant to the function has on the basic parabola.

    Try It 9.110

    Graph f(x)=x2,g(x)=x2+5,f(x)=x2,g(x)=x2+5, and h(x)=x25h(x)=x25 on the same rectangular coordinate system.
    Describe what effect adding a constant to the function has on the basic parabola.

    The last example shows us that to graph a quadratic function of the form f(x)=(xh)2,f(x)=(xh)2, we take the basic parabola graph of f(x)=x2f(x)=x2 and shift it left (h > 0) or shift it right (h < 0).

    This transformation is called a horizontal shift.

    Graph a Quadratic Function of the form f ( x ) = ( x h ) 2 f ( x ) = ( x h ) 2 Using a Horizontal Shift

    The graph of f(x)=(xh)2f(x)=(xh)2 shifts the graph of f(x)=x2f(x)=x2 horizontally hh units.

    • If h > 0, shift the parabola horizontally right h units.
    • If h < 0, shift the parabola horizontally left |h||h| units.

    Now that we have seen the effect of the constant, h, it is easy to graph functions of the form f(x)=(xh)2.f(x)=(xh)2. We just start with the basic parabola of f(x)=x2f(x)=x2 and then shift it left or right.

    The next example will require a horizontal shift.

    Example 9.56

    Graph f(x)=(x6)2f(x)=(x6)2 using a horizontal shift.

    Answer
    We first draw the graph of f(x)=x2f(x)=x2 on
    the grid.
    9.8: Graph Quadratic Functions Using Transformations (12)
    Determine h. 9.8: Graph Quadratic Functions Using Transformations (13)
    9.8: Graph Quadratic Functions Using Transformations (14)
    Shift the graph f(x)=x2f(x)=x2 to the right 6 units. 9.8: Graph Quadratic Functions Using Transformations (15)
    Try It 9.111

    Graph f(x)=(x4)2f(x)=(x4)2 using a horizontal shift.

    Try It 9.112

    Graph f(x)=(x+6)2f(x)=(x+6)2 using a horizontal shift.

    Now that we know the effect of the constants h and k, we will graph a quadratic function of the form f(x)=(xh)2+kf(x)=(xh)2+k by first drawing the basic parabola and then making a horizontal shift followed by a vertical shift. We could do the vertical shift followed by the horizontal shift, but most students prefer the horizontal shift followed by the vertical.

    Example 9.57

    Graph f(x)=(x+1)22f(x)=(x+1)22 using transformations.

    Answer

    This function will involve two transformations and we need a plan.

    Let’s first identify the constants h, k.

    9.8: Graph Quadratic Functions Using Transformations (16)

    The h constant gives us a horizontal shift and the k gives us a vertical shift.

    9.8: Graph Quadratic Functions Using Transformations (17)

    We first draw the graph of f(x)=x2f(x)=x2 on the grid.

    9.8: Graph Quadratic Functions Using Transformations (18) 9.8: Graph Quadratic Functions Using Transformations (19)
    Try It 9.113

    Graph f(x)=(x+2)23f(x)=(x+2)23 using transformations.

    Try It 9.114

    Graph f(x)=(x3)2+1f(x)=(x3)2+1 using transformations.

    Graph Quadratic Functions of the Form f(x)=ax2f(x)=ax2

    So far we graphed the quadratic function f(x)=x2f(x)=x2 and then saw the effect of including a constant h or k in the equation had on the resulting graph of the new function. We will now explore the effect of the coefficient a on the resulting graph of the new function f(x)=ax2.f(x)=ax2.

    9.8: Graph Quadratic Functions Using Transformations (20)

    If we graph these functions, we can see the effect of the constant a, assuming a > 0.

    9.8: Graph Quadratic Functions Using Transformations (21)

    To graph a function with constant a it is easiest to choose a few points on f(x)=x2f(x)=x2 and multiply the y-values by a.

    Graph of a Quadratic Function of the form f ( x ) = a x 2 f ( x ) = a x 2

    The coefficient a in the function f(x)=ax2f(x)=ax2 affects the graph of f(x)=x2f(x)=x2 by stretching or compressing it.

    • If 0<|a|<1,0<|a|<1, the graph of f(x)=ax2f(x)=ax2 will be “wider” than the graph of f(x)=x2.f(x)=x2.
    • If |a|>1|a|>1, the graph of f(x)=ax2f(x)=ax2 will be “skinnier” than the graph of f(x)=x2.f(x)=x2.
    Example 9.58

    Graph f(x)=3x2.f(x)=3x2.

    Answer

    We will graph the functions f(x)=x2f(x)=x2 and g(x)=3x2g(x)=3x2 on the same grid. We will choose a few points on f(x)=x2f(x)=x2 and then multiply the y-values by 3 to get the points for g(x)=3x2.g(x)=3x2.

    9.8: Graph Quadratic Functions Using Transformations (22)
    Try It 9.115

    Graph f(x)=−3x2.f(x)=−3x2.

    Try It 9.116

    Graph f(x)=2x2.f(x)=2x2.

    Graph Quadratic Functions Using Transformations

    We have learned how the constants a, h, and k in the functions, f(x)=x2+k,f(x)=(xh)2,f(x)=x2+k,f(x)=(xh)2, and f(x)=ax2f(x)=ax2 affect their graphs. We can now put this together and graph quadratic functions f(x)=ax2+bx+cf(x)=ax2+bx+c by first putting them into the form f(x)=a(xh)2+kf(x)=a(xh)2+k by completing the square. This form is sometimes known as the vertex form or standard form.

    We must be careful to both add and subtract the number to the SAME side of the function to complete the square. We cannot add the number to both sides as we did when we completed the square with quadratic equations.

    9.8: Graph Quadratic Functions Using Transformations (23)

    When we complete the square in a function with a coefficient of x2 that is not one, we have to factor that coefficient from just the x-terms. We do not factor it from the constant term. It is often helpful to move the constant term a bit to the right to make it easier to focus only on the x-terms.

    Once we get the constant we want to complete the square, we must remember to multiply it by that coefficient before we then subtract it.

    Example 9.59

    Rewrite f(x)=−3x26x1f(x)=−3x26x1 in the f(x)=a(xh)2+kf(x)=a(xh)2+k form by completing the square.

    Answer
    9.8: Graph Quadratic Functions Using Transformations (24)
    Separate the x terms from the constant. 9.8: Graph Quadratic Functions Using Transformations (25)
    Factor the coefficient of x2x2, −3−3. 9.8: Graph Quadratic Functions Using Transformations (26)
    Prepare to complete the square. 9.8: Graph Quadratic Functions Using Transformations (27)
    Take half of 2 and then square it to complete the
    square. (12·2)2=1(12·2)2=1
    The constant 1 completes the square in the
    parentheses, but the parentheses is multiplied by
    −3−3. So we are really adding −3−3 We must then
    add 3 to not change the value of the function.
    9.8: Graph Quadratic Functions Using Transformations (28)
    Rewrite the trinomial as a square and subtract the
    constants.
    9.8: Graph Quadratic Functions Using Transformations (29)
    The function is now in the f(x)=a(xh)2+kf(x)=a(xh)2+k
    form.
    9.8: Graph Quadratic Functions Using Transformations (30)
    Try It 9.117

    Rewrite f(x)=−4x28x+1f(x)=−4x28x+1 in the f(x)=a(xh)2+kf(x)=a(xh)2+k form by completing the square.

    Try It 9.118

    Rewrite f(x)=2x28x+3f(x)=2x28x+3 in the f(x)=a(xh)2+kf(x)=a(xh)2+k form by completing the square.

    Once we put the function into the f(x)=(xh)2+kf(x)=(xh)2+k form, we can then use the transformations as we did in the last few problems. The next example will show us how to do this.

    Example 9.60

    Graph f(x)=x2+6x+5f(x)=x2+6x+5 by using transformations.

    Answer

    Step 1. Rewrite the function in f(x)=a(xh)2+kf(x)=a(xh)2+k vertex form by completing the square.

    9.8: Graph Quadratic Functions Using Transformations (31)
    Separate the x terms from the constant. 9.8: Graph Quadratic Functions Using Transformations (32)
    Take half of 6 and then square it to complete the square.
    (12·6)2=9(12·6)2=9
    We both add 9 and subtract 9 to not change the value of the function. 9.8: Graph Quadratic Functions Using Transformations (33)
    Rewrite the trinomial as a square and subtract the constants. 9.8: Graph Quadratic Functions Using Transformations (34)
    The function is now in the f(x)=(xh)2+kf(x)=(xh)2+k form. 9.8: Graph Quadratic Functions Using Transformations (35)

    Step 2: Graph the function using transformations.

    Looking at the h, k values, we see the graph will take the graph of f(x)=x2f(x)=x2 and shift it to the left 3 units and down 4 units.

    9.8: Graph Quadratic Functions Using Transformations (36)

    We first draw the graph of f(x)=x2f(x)=x2 on the grid.

    9.8: Graph Quadratic Functions Using Transformations (37) 9.8: Graph Quadratic Functions Using Transformations (38)
    Try It 9.119

    Graph f(x)=x2+2x3f(x)=x2+2x3 by using transformations.

    Try It 9.120

    Graph f(x)=x28x+12f(x)=x28x+12 by using transformations.

    We list the steps to take to graph a quadratic function using transformations here.

    How To

    Graph a quadratic function using transformations.

    1. Step 1. Rewrite the function in f(x)=a(xh)2+kf(x)=a(xh)2+k form by completing the square.
    2. Step 2. Graph the function using transformations.
    Example 9.61

    Graph f(x)=−2x24x+2f(x)=−2x24x+2 by using transformations.

    Answer

    Step 1. Rewrite the function in f(x)=a(xh)2+kf(x)=a(xh)2+k vertex form by completing the square.

    9.8: Graph Quadratic Functions Using Transformations (39)
    Separate the x terms from the constant. 9.8: Graph Quadratic Functions Using Transformations (40)
    We need the coefficient of x2x2 to be one.
    We factor −2−2 from the x-terms.
    9.8: Graph Quadratic Functions Using Transformations (41)
    Take half of 2 and then square it to complete the square.
    (12·2)2=1(12·2)2=1
    We add 1 to complete the square in the parentheses, but the parentheses is multiplied by −2−2. Se we are really adding −2−2. To not change the value of the function we add 2. 9.8: Graph Quadratic Functions Using Transformations (42)
    Rewrite the trinomial as a square and subtract the constants. 9.8: Graph Quadratic Functions Using Transformations (43)
    The function is now in the f(x)=a(xh)2+kf(x)=a(xh)2+k form. 9.8: Graph Quadratic Functions Using Transformations (44)

    Step 2. Graph the function using transformations.

    9.8: Graph Quadratic Functions Using Transformations (45)

    We first draw the graph of f(x)=x2f(x)=x2 on the grid.

    9.8: Graph Quadratic Functions Using Transformations (46) 9.8: Graph Quadratic Functions Using Transformations (47)
    Try It 9.121

    Graph f(x)=−3x2+12x4f(x)=−3x2+12x4 by using transformations.

    Try It 9.122

    Graph f(x)=−2x2+12x9f(x)=−2x2+12x9 by using transformations.

    Now that we have completed the square to put a quadratic function into f(x)=a(xh)2+kf(x)=a(xh)2+k form, we can also use this technique to graph the function using its properties as in the previous section.

    If we look back at the last few examples, we see that the vertex is related to the constants h and k.

    9.8: Graph Quadratic Functions Using Transformations (48)

    In each case, the vertex is (h, k). Also the axis of symmetry is the line x = h.

    We rewrite our steps for graphing a quadratic function using properties for when the function is in f(x)=a(xh)2+kf(x)=a(xh)2+k form.

    How To

    Graph a quadratic function in the form f(x)=a(xh)2+kf(x)=a(xh)2+k using properties.

    1. Step 1. Rewrite the function in f(x)=a(xh)2+kf(x)=a(xh)2+k form.
    2. Step 2. Determine whether the parabola opens upward, a > 0, or downward, a < 0.
    3. Step 3. Find the axis of symmetry, x = h.
    4. Step 4. Find the vertex, (h, k).
    5. Step 5. Find the y-intercept. Find the point symmetric to the y-intercept across the axis of symmetry.
    6. Step 6. Find the x-intercepts.
    7. Step 7. Graph the parabola.
    Example 9.62

    Rewrite f(x)=2x2+4x+5f(x)=2x2+4x+5 in f(x)=a(xh)2+kf(x)=a(xh)2+k form and graph the function using properties.

    Answer
    Rewrite the function in f(x)=a(xh)2+kf(x)=a(xh)2+k
    form by completing the square.
    f(x)=2x2+4x+5f(x)=2x2+4x+5
    f(x)=2(x2+2x)+5f(x)=2(x2+2x)+5
    f(x)=2(x2+2x+1)+52f(x)=2(x2+2x+1)+52
    f(x)=2(x+1)2+3f(x)=2(x+1)2+3
    Identify the constants a,h,k.a,h,k. a=2h=−1k=3a=2h=−1k=3
    Since a=2a=2, the parabola opens upward. 9.8: Graph Quadratic Functions Using Transformations (49)
    The axis of symmetry is x=hx=h. The axis of symmetry is x=−1x=−1.
    The vertex is (h,k)(h,k). The vertex is (−1,3)(−1,3).
    Find the y-intercept by finding f(0)f(0). f(0)=202+40+5f(0)=202+40+5
    f(0)=5f(0)=5
    y-intercept (0,5)(0,5)
    Find the point symmetric to (0,5)(0,5) across the
    axis of symmetry.
    (2,5)(2,5)
    Find the x-intercepts. The discriminant negative, so there are
    no x-intercepts. Graph the parabola.
    9.8: Graph Quadratic Functions Using Transformations (50)
    Try It 9.123

    Rewrite f(x)=3x26x+5f(x)=3x26x+5 in f(x)=a(xh)2+kf(x)=a(xh)2+k form and graph the function using properties.

    Try It 9.124

    Rewrite f(x)=−2x2+8x7f(x)=−2x2+8x7 in f(x)=a(xh)2+kf(x)=a(xh)2+k form and graph the function using properties.

    Find a Quadratic Function from its Graph

    So far we have started with a function and then found its graph.

    Now we are going to reverse the process. Starting with the graph, we will find the function.

    Example 9.63

    Determine the quadratic function whose graph is shown.

    9.8: Graph Quadratic Functions Using Transformations (51)

    Answer
    Since it is quadratic, we start with the f(x)=a(xh)2+kform.f(x)=a(xh)2+kform.
    The vertex, (h,k),(h,k), is (−2,−1)(−2,−1) so h=−2h=−2 and k=−1.k=−1. f(x)=a(x(−2))21f(x)=a(x(−2))21
    To find aa, we use the yy-intercept, (0,7)(0,7).
    So f(0)=7f(0)=7. 7=a(0+2)217=a(0+2)21
    Solve for aa. 7=4a17=4a1
    8=4a8=4a
    2=a2=a
    Write the function. f(x)=a(xh)2+kf(x)=a(xh)2+k
    Substitute in h=−2,k=−1h=−2,k=−1 and a=2a=2. f(x)=2(x+2)21f(x)=2(x+2)21
    Try It 9.125

    Write the quadratic function in f(x)=a(xh)2+kf(x)=a(xh)2+k form whose graph is shown.

    9.8: Graph Quadratic Functions Using Transformations (52)

    Try It 9.126

    Determine the quadratic function whose graph is shown.

    9.8: Graph Quadratic Functions Using Transformations (53)

    Section 9.7 Exercises

    Practice Makes Perfect

    Graph Quadratic Functions of the form f(x)=x2+kf(x)=x2+k

    In the following exercises, graph the quadratic functions on the same rectangular coordinate system and describe what effect adding a constant, k, to the function has on the basic parabola.

    293.

    f(x)=x2,g(x)=x2+4,f(x)=x2,g(x)=x2+4, and h(x)=x24.h(x)=x24.

    294.

    f(x)=x2,g(x)=x2+7,f(x)=x2,g(x)=x2+7, and h(x)=x27.h(x)=x27.

    In the following exercises, graph each function using a vertical shift.

    295.

    f ( x ) = x 2 + 3 f ( x ) = x 2 + 3

    296.

    f ( x ) = x 2 7 f ( x ) = x 2 7

    297.

    g ( x ) = x 2 + 2 g ( x ) = x 2 + 2

    298.

    g ( x ) = x 2 + 5 g ( x ) = x 2 + 5

    299.

    h ( x ) = x 2 4 h ( x ) = x 2 4

    300.

    h ( x ) = x 2 5 h ( x ) = x 2 5

    Graph Quadratic Functions of the form f(x)=(xh)2f(x)=(xh)2

    In the following exercises, graph the quadratic functions on the same rectangular coordinate system and describe what effect adding a constant, hh, inside the parentheses has

    301.

    f(x)=x2,g(x)=(x3)2,f(x)=x2,g(x)=(x3)2, and h(x)=(x+3)2.h(x)=(x+3)2.

    302.

    f(x)=x2,g(x)=(x+4)2,f(x)=x2,g(x)=(x+4)2, and h(x)=(x4)2.h(x)=(x4)2.

    In the following exercises, graph each function using a horizontal shift.

    303.

    f ( x ) = ( x 2 ) 2 f ( x ) = ( x 2 ) 2

    304.

    f ( x ) = ( x 1 ) 2 f ( x ) = ( x 1 ) 2

    305.

    f ( x ) = ( x + 5 ) 2 f ( x ) = ( x + 5 ) 2

    306.

    f ( x ) = ( x + 3 ) 2 f ( x ) = ( x + 3 ) 2

    307.

    f ( x ) = ( x 5 ) 2 f ( x ) = ( x 5 ) 2

    308.

    f ( x ) = ( x + 2 ) 2 f ( x ) = ( x + 2 ) 2

    In the following exercises, graph each function using transformations.

    309.

    f ( x ) = ( x + 2 ) 2 + 1 f ( x ) = ( x + 2 ) 2 + 1

    310.

    f ( x ) = ( x + 4 ) 2 + 2 f ( x ) = ( x + 4 ) 2 + 2

    311.

    f ( x ) = ( x 1 ) 2 + 5 f ( x ) = ( x 1 ) 2 + 5

    312.

    f ( x ) = ( x 3 ) 2 + 4 f ( x ) = ( x 3 ) 2 + 4

    313.

    f ( x ) = ( x + 3 ) 2 1 f ( x ) = ( x + 3 ) 2 1

    314.

    f ( x ) = ( x + 5 ) 2 2 f ( x ) = ( x + 5 ) 2 2

    315.

    f ( x ) = ( x 4 ) 2 3 f ( x ) = ( x 4 ) 2 3

    316.

    f ( x ) = ( x 6 ) 2 2 f ( x ) = ( x 6 ) 2 2

    Graph Quadratic Functions of the form f(x)=ax2f(x)=ax2

    In the following exercises, graph each function.

    317.

    f ( x ) = −2 x 2 f ( x ) = −2 x 2

    318.

    f ( x ) = 4 x 2 f ( x ) = 4 x 2

    319.

    f ( x ) = −4 x 2 f ( x ) = −4 x 2

    320.

    f ( x ) = x 2 f ( x ) = x 2

    321.

    f ( x ) = 1 2 x 2 f ( x ) = 1 2 x 2

    322.

    f ( x ) = 1 3 x 2 f ( x ) = 1 3 x 2

    323.

    f ( x ) = 1 4 x 2 f ( x ) = 1 4 x 2

    324.

    f ( x ) = 1 2 x 2 f ( x ) = 1 2 x 2

    Graph Quadratic Functions Using Transformations

    In the following exercises, rewrite each function in the f(x)=a(xh)2+kf(x)=a(xh)2+k form by completing the square.

    325.

    f ( x ) = −3 x 2 12 x 5 f ( x ) = −3 x 2 12 x 5

    326.

    f ( x ) = 2 x 2 12 x + 7 f ( x ) = 2 x 2 12 x + 7

    327.

    f ( x ) = 3 x 2 + 6 x 1 f ( x ) = 3 x 2 + 6 x 1

    328.

    f ( x ) = −4 x 2 16 x 9 f ( x ) = −4 x 2 16 x 9

    In the following exercises, rewrite each function in f(x)=a(xh)2+kf(x)=a(xh)2+k form and graph it by using transformations.

    329.

    f ( x ) = x 2 + 6 x + 5 f ( x ) = x 2 + 6 x + 5

    330.

    f ( x ) = x 2 + 4 x 12 f ( x ) = x 2 + 4 x 12

    331.

    f ( x ) = x 2 + 4 x + 3 f ( x ) = x 2 + 4 x + 3

    332.

    f ( x ) = x 2 6 x + 8 f ( x ) = x 2 6 x + 8

    333.

    f ( x ) = x 2 6 x + 15 f ( x ) = x 2 6 x + 15

    334.

    f ( x ) = x 2 + 8 x + 10 f ( x ) = x 2 + 8 x + 10

    335.

    f ( x ) = x 2 + 8 x 16 f ( x ) = x 2 + 8 x 16

    336.

    f ( x ) = x 2 + 2 x 7 f ( x ) = x 2 + 2 x 7

    337.

    f ( x ) = x 2 4 x + 2 f ( x ) = x 2 4 x + 2

    338.

    f ( x ) = x 2 + 4 x 5 f ( x ) = x 2 + 4 x 5

    339.

    f ( x ) = 5 x 2 10 x + 8 f ( x ) = 5 x 2 10 x + 8

    340.

    f ( x ) = 3 x 2 + 18 x + 20 f ( x ) = 3 x 2 + 18 x + 20

    341.

    f ( x ) = 2 x 2 4 x + 1 f ( x ) = 2 x 2 4 x + 1

    342.

    f ( x ) = 3 x 2 6 x 1 f ( x ) = 3 x 2 6 x 1

    343.

    f ( x ) = −2 x 2 + 8 x 10 f ( x ) = −2 x 2 + 8 x 10

    344.

    f ( x ) = −3 x 2 + 6 x + 1 f ( x ) = −3 x 2 + 6 x + 1

    In the following exercises, rewrite each function in f(x)=a(xh)2+kf(x)=a(xh)2+k form and graph it using properties.

    345.

    f ( x ) = 2 x 2 + 4 x + 6 f ( x ) = 2 x 2 + 4 x + 6

    346.

    f ( x ) = 3 x 2 12 x + 7 f ( x ) = 3 x 2 12 x + 7

    347.

    f ( x ) = x 2 + 2 x 4 f ( x ) = x 2 + 2 x 4

    348.

    f ( x ) = −2 x 2 4 x 5 f ( x ) = −2 x 2 4 x 5

    Matching

    In the following exercises, match the graphs to one of the following functions: f(x)=x2+4f(x)=x2+4 f(x)=x24f(x)=x24 f(x)=(x+4)2f(x)=(x+4)2 f(x)=(x4)2f(x)=(x4)2 f(x)=(x+4)24f(x)=(x+4)24 f(x)=(x+4)2+4f(x)=(x+4)2+4 f(x)=(x4)24f(x)=(x4)24 f(x)=(x4)2+4f(x)=(x4)2+4

    349.

    9.8: Graph Quadratic Functions Using Transformations (54)

    350.

    9.8: Graph Quadratic Functions Using Transformations (55)

    351.

    9.8: Graph Quadratic Functions Using Transformations (56)

    352.

    9.8: Graph Quadratic Functions Using Transformations (57)

    353.

    9.8: Graph Quadratic Functions Using Transformations (58)

    354.

    9.8: Graph Quadratic Functions Using Transformations (59)

    355.

    9.8: Graph Quadratic Functions Using Transformations (60)

    356.

    9.8: Graph Quadratic Functions Using Transformations (61)

    Find a Quadratic Function from its Graph

    In the following exercises, write the quadratic function in f(x)=a(xh)2+kf(x)=a(xh)2+k form whose graph is shown.

    357.

    9.8: Graph Quadratic Functions Using Transformations (62)

    358.

    9.8: Graph Quadratic Functions Using Transformations (63)

    359.

    9.8: Graph Quadratic Functions Using Transformations (64)

    360.

    9.8: Graph Quadratic Functions Using Transformations (65)

    Writing Exercise

    361.

    Graph the quadratic function f(x)=x2+4x+5f(x)=x2+4x+5 first using the properties as we did in the last section and then graph it using transformations. Which method do you prefer? Why?

    362.

    Graph the quadratic function f(x)=2x24x3f(x)=2x24x3 first using the properties as we did in the last section and then graph it using transformations. Which method do you prefer? Why?

    Self Check

    After completing the exercises, use this checklist to evaluate your mastery of the objectives of this section.

    9.8: Graph Quadratic Functions Using Transformations (66)

    After looking at the checklist, do you think you are well-prepared for the next section? Why or why not?

    9.8: Graph Quadratic Functions Using Transformations (2024)

    FAQs

    How do you graph a transformed quadratic function? ›

    Graph a Quadratic Function in the Form f(x)=a(x−h)2+k Using Properties
    1. Rewrite the function f(x)=a(x−h)2+k form.
    2. Determine whether the parabola opens upward, a>0, or downward, a<0.
    3. Find the axis of symmetry, x=h.
    4. Find the vertex, (h,k.
    5. Find the y-intercept. ...
    6. Find the x-intercepts.
    7. Graph the parabola.
    Dec 16, 2019

    How do you graph a function using transformations? ›

    5 Steps To Graph Function Transformations In Algebra
    1. Identify The Parent Function. ...
    2. Reflect Over X-Axis or Y-Axis. ...
    3. Shift (Translate) Vertically or Horizontally. ...
    4. Vertical and Horizontal Stretches/Compressions. ...
    5. Plug in a couple of your coordinates into the parent function to double check your work.
    Jan 24, 2017

    What is the rule for quadratic transformation? ›

    The parent function of the quadratic family is f(x) = x2. A transformation of the graph of the parent function is represented by the function g(x) = a(x − h)2 + k, where a ≠ 0.

    What is a method used to transform quadratic functions? ›

    Completing the square is a method that can be used to transform a quadratic equation in standard form to vertex form. Once in vertex form, a quadratic equation is easy to graph or solve. In other words, these two terms are equal to one another, so we are able to convert from one to the other.

    How to tell how many solutions a quadratic graph has? ›

    If b2 - 4ac is positive (>0) then we have 2 solutions. If b2 - 4ac is 0 then we have only one solution as the formula is reduced to x = [-b ± 0]/2a. So x = -b/2a, giving only one solution. Lastly, if b2 - 4ac is less than 0 we have no solutions.

    What is the formula to graph quadratic equations? ›

    The U-shaped graph of any quadratic function defined by f(x)=ax2+bx+c, where a, b, and c are real numbers and a≠0. The point that defines the minimum or maximum of a parabola. The vertical line through the vertex, x=−b2a, about which the parabola is symmetric. A term used when referencing the line of symmetry.

    How to solve quadratic functions? ›

    The quadratic formula helps us solve any quadratic equation. First, we bring the equation to the form ax²+bx+c=0, where a, b, and c are coefficients. Then, we plug these coefficients in the formula: (-b±√(b²-4ac))/(2a) . See examples of using the formula to solve a variety of equations.

    How to plot a parabola graph? ›

    Given y = ax2 + bx + c , we have to go through the following steps to find the points and shape of any parabola:
    1. Label a, b, and c.
    2. Decide the direction of the paraola:
    3. Find the x-intercepts:
    4. Find the y-intercept:
    5. Find the vertex (h,k):
    6. Plot the points and graph the parabola.

    How do you graph translations? ›

    To move a graph up, we add a positive value to the y-value. To move a graph down, we add a negative value to the y-value. To move a graph right, we add a negative value to the x-value. To move a graph left, we add a positive value to the x-value.

    How is the graph of the parent quadratic function transformed to produce the graph? ›

    Answer: The graph is reflected over the x-axis, compressed horizontally by a factor of 2, shifted left 6 units, and translated up 3 units.

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