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Comparing smooth and continuous graphs

The degree of a polynomial function helps us to determine the number of x -intercepts and the number of turning points. A polynomial function of n th degree is the product of n factors, so it will have at most n roots or zeros, or x -intercepts. The graph of the polynomial function of degree n must have at most n 1 turning points. This means the graph has at most one fewer turning point than the degree of the polynomial or one fewer than the number of factors.

A continuous function    has no breaks in its graph: the graph can be drawn without lifting the pen from the paper. A smooth curve    is a graph that has no sharp corners. The turning points of a smooth graph must always occur at rounded curves. The graphs of polynomial functions are both continuous and smooth.

Intercepts and turning points of polynomials

A polynomial of degree n will have, at most, n x -intercepts and n 1 turning points.

Determining the number of intercepts and turning points of a polynomial

Without graphing the function, determine the local behavior of the function by finding the maximum number of x -intercepts and turning points for f ( x ) = 3 x 10 + 4 x 7 x 4 + 2 x 3 .

The polynomial has a degree of 10 , so there are at most 10 x -intercepts and at most 9 turning points.

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Without graphing the function, determine the maximum number of x -intercepts and turning points for f ( x ) = 108 13 x 9 8 x 4 + 14 x 12 + 2 x 3 .

There are at most 12 x - intercepts and at most 11 turning points.

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Drawing conclusions about a polynomial function from the graph

What can we conclude about the polynomial represented by the graph shown in [link] based on its intercepts and turning points?

Graph of an even-degree polynomial.

The end behavior of the graph tells us this is the graph of an even-degree polynomial. See [link] .

Graph of an even-degree polynomial that denotes the turning points and intercepts.

The graph has 2 x -intercepts, suggesting a degree of 2 or greater, and 3 turning points, suggesting a degree of 4 or greater. Based on this, it would be reasonable to conclude that the degree is even and at least 4.

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What can we conclude about the polynomial represented by the graph shown in [link] based on its intercepts and turning points?

Graph of an odd-degree polynomial.

The end behavior indicates an odd-degree polynomial function; there are 3 x - intercepts and 2 turning points, so the degree is odd and at least 3. Because of the end behavior, we know that the lead coefficient must be negative.

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Drawing conclusions about a polynomial function from the factors

Given the function f ( x ) = 4 x ( x + 3 ) ( x 4 ) , determine the local behavior.

The y -intercept is found by evaluating f ( 0 ) .

f ( 0 ) = 4 ( 0 ) ( 0 + 3 ) ( 0 4 = 0

The y -intercept is ( 0 , 0 ) .

The x -intercepts are found by determining the zeros of the function.

0 = −4 x ( x + 3 ) ( x 4 )
x = 0 or x + 3 = 0 or x 4 = 0 x = 0 or x = 3 or x = 4

The x -intercepts are ( 0 , 0 ) , ( –3 , 0 ) , and ( 4 , 0 ) .

The degree is 3 so the graph has at most 2 turning points.

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Given the function f ( x ) = 0.2 ( x 2 ) ( x + 1 ) ( x 5 ) , determine the local behavior.

The x - intercepts are ( 2 , 0 ) , ( 1 , 0 ) , and ( 5 , 0 ) , the y- intercept is ( 0 , 2 ) , and the graph has at most 2 turning points.

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Questions & Answers

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The sum of the first n terms of a certain series is 2^n-1, Show that , this series is Geometric and Find the formula of the n^th
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cosA\1+sinA=secA-tanA
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why two x + seven is equal to nineteen.
Kingsley Reply
The numbers cannot be combined with the x
Othman
2x + 7 =19
humberto
2x +7=19. 2x=19 - 7 2x=12 x=6
Yvonne
because x is 6
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simplify each radical by removing as many factors as possible (a) √75
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how is infinity bidder from undefined?
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what is the value of x in 4x-2+3
Vishal Reply
give the complete question
Shanky
4x=3-2 4x=1 x=1+4 x=5 5x
Olaiya
hi can you give another equation I'd like to solve it
Daniel
what is the value of x in 4x-2+3
Olaiya
if 4x-2+3 = 0 then 4x = 2-3 4x = -1 x = -(1÷4) is the answer.
Jacob
4x-2+3 4x=-3+2 4×=-1 4×/4=-1/4
LUTHO
then x=-1/4
LUTHO
4x-2+3 4x=-3+2 4x=-1 4x÷4=-1÷4 x=-1÷4
LUTHO
A research student is working with a culture of bacteria that doubles in size every twenty minutes. The initial population count was  1350  bacteria. Rounding to five significant digits, write an exponential equation representing this situation. To the nearest whole number, what is the population size after  3  hours?
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A guy wire for a suspension bridge runs from the ground diagonally to the top of the closest pylon to make a triangle. We can use the Pythagorean Theorem to find the length of guy wire needed. The square of the distance between the wire on the ground and the pylon on the ground is 90,000 feet. The square of the height of the pylon is 160,000 feet. So, the length of the guy wire can be found by evaluating √(90000+160000). What is the length of the guy wire?
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Source:  OpenStax, Algebra and trigonometry. OpenStax CNX. Nov 14, 2016 Download for free at https://legacy.cnx.org/content/col11758/1.6
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