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5.3 Graphs of Polynomial Functions

Zeros from factored form and how multiplicity makes a curve cross or merely touch the axis, counting turning points, and the Intermediate Value Theorem.

Algebra and Trigonometry 2e, 5.3 Graphs of Polynomial Functions

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39 exercises

Solve a quadratic equation by factoring

Solve (4x-1)(x+6)=0\left(4 x - 1\right) \left(x + 6\right) = 0

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Solve a quadratic equation by factoring

x2-2x=63x^{2} - 2 x = 63

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Finding the y - and x -Intercepts of a Polynomial in Factored Form

Find the y- and x-intercepts of g(x)= (x−2) 2 (2x+3). g \left(x\right) = \left(x - 2\right)^{2} \left(2 x + 3\right) .

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5.3 Exercise 22

Find the y- and x-intercepts of the function f(x)= x 4 −19 x 2 +30x. f \left(x\right) = x^{4} - 19 x^{2} + 30 x .

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Using the Intermediate Value Theorem

Show that the function f(x)= x 3 −5 x 2 +3x+6 f \left(x\right) = x^{3} - 5 x^{2} + 3 x + 6 has at least two real zeros between x=1 x = 1 and x=4. x = 4.

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5.3 Exercise 29

Show that the function f(x)=7 x 5 −9 x 4 − x 2 f \left(x\right) = 7 x^{5} - 9 x^{4} - x^{2} has at least one real zero between x=1 x = 1 and x=2. x = 2.

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5.3 Exercise 33

Use technology to find the maximum and minimum values on the interval [−1,4] \left[−1 , 4\right] of the function f(x)=−0.2 (x−2) 3 (x+1) 2 (x−4). f \left(x\right) = - 0.2 \left(x - 2\right)^{3} \left(x + 1\right)^{2} \left(x - 4\right) .

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5.3 Exercise 34

What is the difference between an x- x - intercept and a zero of a polynomial function f? f ?

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5.3 Exercise 36

Explain how the Intermediate Value Theorem can assist us in finding a zero of a function.

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5.3 Exercise 38

If the graph of a polynomial just touches the x-axis and then changes direction, what can we conclude about the factored form of the polynomial?

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5.3 Exercise 40

Find the x- x - or t-intercepts of the polynomial functions.

C( t )=3( t+2 )( t−3 )(t+5) C \left(t\right) = 3 \left(t + 2\right) \left(t - 3\right) \left(t + 5\right)

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5.3 Exercise 42

Find the x- x - or t-intercepts of the polynomial functions.

C( t )=2t( t−3 ) ( t+1 ) 2 C \left(t\right) = 2 t \left(t - 3\right) \left(t + 1\right)^{2}

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5.3 Exercise 44

Find the x- x - or t-intercepts of the polynomial functions.

C( t )=4 t 4 +12 t 3 −40 t 2 C \left(t\right) = 4 t^{4} + 12 t^{3} - 40 t^{2}

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5.3 Exercise 46

Find the x- x - or t-intercepts of the polynomial functions.

f(x)= x 3 + x 2 −20x f \left(x\right) = x^{3} + x^{2} - 20 x

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5.3 Exercise 48

Find the x- x - or t-intercepts of the polynomial functions.

f(x)= x 3 + x 2 −4x−4 f \left(x\right) = x^{3} + x^{2} - 4 x - 4

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5.3 Exercise 50

Find the x- x - or t-intercepts of the polynomial functions.

f(x)=2 x 3 − x 2 −8x+4 f \left(x\right) = 2 x^{3} - x^{2} - 8 x + 4

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5.3 Exercise 52

Find the x- x - or t-intercepts of the polynomial functions.

f(x)=2 x 4 +6 x 2 −8 f \left(x\right) = 2 x^{4} + 6 x^{2} - 8

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5.3 Exercise 54

Find the x- x - or t-intercepts of the polynomial functions.

f(x)= x 6 −2 x 4 −3 x 2 f \left(x\right) = x^{6} - 2 x^{4} - 3 x^{2}

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5.3 Exercise 56

Find the x- x - or t-intercepts of the polynomial functions.

f(x)= x 5 −5 x 3 +4x f \left(x\right) = x^{5} - 5 x^{3} + 4 x

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5.3 Exercise 58

Use the Intermediate Value Theorem to confirm that the given polynomial has at least one zero within the given interval.

f(x)= x 3 −9x, f \left(x\right) = x^{3} - 9 x , between x=2 x = 2 and x=4. x = 4.

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5.3 Exercise 60

Use the Intermediate Value Theorem to confirm that the given polynomial has at least one zero within the given interval.

f(x)=− x 4 +4, f \left(x\right) = - x^{4} + 4 , between x=1 x = 1 and x=3 x = 3 .

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5.3 Exercise 62

Use the Intermediate Value Theorem to confirm that the given polynomial has at least one zero within the given interval.

f(x)= x 3 −100x+2, f \left(x\right) = x^{3} - 100 x + 2 , between x=0.01 x = 0.01 and x=0.1 x = 0.1

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5.3 Exercise 64

Find the zeros and give the multiplicity of each.

f(x)= x 2 ( 2x+3 ) 5 ( x−4 ) 2 f \left(x\right) = x^{2} \left(2 x + 3\right)^{5} \left(x - 4\right)^{2}

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5.3 Exercise 66

Find the zeros and give the multiplicity of each.

f(x)= x 2 ( x 2 +4x+4 ) f \left(x\right) = x^{2} \left(x^{2} + 4 x + 4\right)

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5.3 Exercise 68

Find the zeros and give the multiplicity of each.

f(x)= ( 3x+2 ) 5 ( x 2 −10x+25 ) f \left(x\right) = \left(3 x + 2\right)^{5} \left(x^{2} - 10 x + 25\right)

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5.3 Exercise 70

Find the zeros and give the multiplicity of each.

f(x)= x 6 − x 5 −2 x 4 f \left(x\right) = x^{6} - x^{5} - 2 x^{4}

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5.3 Exercise 72

Find the zeros and give the multiplicity of each.

f(x)=4 x 5 −12 x 4 +9 x 3 f \left(x\right) = 4 x^{5} - 12 x^{4} + 9 x^{3}

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5.3 Exercise 74

Find the zeros and give the multiplicity of each.

f(x)=4 x 4 ( 9 x 4 −12 x 3 +4 x 2 ) f \left(x\right) = 4 x^{4} \left(9 x^{4} - 12 x^{3} + 4 x^{2}\right)

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5.3 Exercise 90

Use the given information about the polynomial graph to write the equation.

Degree 3. Zeros at x=–2, x = –2, x=1, x = 1, and x=3. x = 3. y-intercept at (0,–4). \left(0 , –4\right) .

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5.3 Exercise 92

Use the given information about the polynomial graph to write the equation.

Degree 5. Roots of multiplicity 2 at x=3 x = 3 and x=1 x = 1 , and a root of multiplicity 1 at x=–3. x = –3. y-intercept at (0,9) \left(0 , 9\right)

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5.3 Exercise 94

Use the given information about the polynomial graph to write the equation.

Degree 5. Double zero at x=1, x = 1 , and triple zero at x=3. x = 3. Passes through the point (2,15). \left(2 , 15\right) .

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5.3 Exercise 96

Use the given information about the polynomial graph to write the equation.

Degree 3. Zeros at x=−3, x = −3 , x=−2 x = −2 and x=1. x = 1. y-intercept at (0,12). \left(0 , 12\right) .

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5.3 Exercise 98

Use the given information about the polynomial graph to write the equation.

Degree 4. Roots of multiplicity 2 at x= 1 2 x = \frac{1}{2} and roots of multiplicity 1 at x=6 x = 6 and x=−2. x = −2.

y-intercept at ( 0,18 ). \left(0, 18\right) .

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5.3 Exercise 100

Use a calculator to approximate local minima and maxima or the global minimum and maximum.

f(x)= x 3 −x−1 f \left(x\right) = x^{3} - x - 1

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5.3 Exercise 102

Use a calculator to approximate local minima and maxima or the global minimum and maximum.

f(x)= x 4 +x f \left(x\right) = x^{4} + x

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5.3 Exercise 104

Use a calculator to approximate local minima and maxima or the global minimum and maximum.

f(x)= x 4 − x 3 +1 f \left(x\right) = x^{4} - x^{3} + 1

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5.3 Exercise 108

Write the polynomial function that models the given situation.

A rectangle has a length of 10 units and a width of 8 units. Squares of x x by x x units are cut out of each corner, and then the sides are folded up to create an open box. Express the volume of the box as a polynomial function in terms of x. x .

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5.3 Exercise 110

Write the polynomial function that models the given situation.

A square has sides of 12 units. Squares x+1 x + 1 by x+1 x + 1 units are cut out of each corner, and then the sides are folded up to create an open box. Express the volume of the box as a function in terms of x. x .

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5.3 Exercise 112

Write the polynomial function that models the given situation.

A right circular cone has a radius of 3x+6 3 x + 6 and a height 3 units less. Express the volume of the cone as a polynomial function. The volume of a cone is V= 1 3 π r 2 h V = \frac{1}{3} \pi r^{2} h for radius r r and height h. h .

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Adapted from College Algebra © 2021 Rice University. Licensed under CC BY 4.0. Sources: College Algebra 2e, Algebra and Trigonometry 2e, Precalculus 2e, College Algebra with Corequisite Support 2e. Imported at revision 4922e46.