Algebra II : Polynomial Functions

Study concepts, example questions & explanations for Algebra II

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Example Questions

Example Question #31 : Polynomial Functions

A baseball is thrown off the roof of a building 220 feet high at an initial upward speed of 72 feet per second; the height of the baseball relative to the ground is modeled by the function

How long does it take for the baseball to reach its highest point (nearest tenth of a second)?

Possible Answers:

Correct answer:

Explanation:

The highest point of the ball is the vertex of the ball's parabolic path, so to find the number of seconds  that is takes to reach this point, it is necessary to find the vertex of the parabola of the graph of the function

The parabola of the graph of 

has as its ordinate, or -coordinate,

,

so, setting ,

,

which rounds to 2.3 seconds. This is the time that it takes the ball to reach the highest point of its path.

Example Question #31 : Polynomial Functions

A baseball is thrown off the roof of a building 220 feet high at an initial upward speed of 72 feet per second; the height of the baseball relative to the ground is modeled by the function

How long does it take for the baseball to hit the ground (nearest tenth of a second)?

Possible Answers:

Correct answer:

Explanation:

When the baseball hits the ground, its height is 0; therefore, we are looking for  such that 

,

or

This equation can most easily be solved using the quadratic formula. If 

,

then 

Setting :

One possible answer is 

We throw this out, since we cannot have "negative time".

The other is 

This is positive, so we accept this answer. The ball hits the ground in about 6.6 seconds.

Example Question #33 : Polynomial Functions

Find the product:

Possible Answers:

Correct answer:

Explanation:

Using the FOIL (first, outer, inner, last) method, you can expand the polynomial to get 

first: 

outer: 

inner: 

lasts: 

From here, combine the like terms.

Example Question #581 : Functions And Graphs

What are the roots of ?

Possible Answers:

Correct answer:

Explanation:

In order to find the roots, we must factor the equation.

The factors of this equation are  and .

Setting those two equal to zero, we get  and .

Example Question #1 : Graphing Polynomial Functions

Where does the graph of cross the axis?

Possible Answers:

Correct answer:

Explanation:

To find where the graph crosses the horizontal axis, we need to set the function equal to 0, since the value at any point along the axis is always zero.

To find the possible rational zeroes of a polynomial, use the rational zeroes theorem:

Our constant is 10, and our leading coefficient is 1. So here are our possible roots:

Let's try all of them and see if they work! We're going to substitute each value in for using synthetic substitution. We'll try -1 first.

Looks like that worked! We got 0 as our final answer after synthetic substitution. What's left in the bottom row helps us factor down a little farther:

We keep doing this process until is completely factored:

Thus, crosses the axis at .

Example Question #2 : Graphing Other Functions

Where does cross the axis?

Possible Answers:

5

7

-3

-7

3

Correct answer:

7

Explanation:

crosses the axis when equals 0. So, substitute in 0 for :

Example Question #1 : Graphing Polynomial Functions

Which equation best represents the following graph?

Graph6

Possible Answers:

None of these

Correct answer:

Explanation:

We have the following answer choices.

The first equation is a cubic function, which produces a function similar to the graph. The second equation is quadratic and thus, a parabola. The graph does not look like a prabola, so the 2nd equation will be incorrect. The third equation describes a line, but the graph is not linear; the third equation is incorrect. The fourth equation is incorrect because it is an exponential, and the graph is not an exponential. So that leaves the first equation as the best possible choice.

Example Question #1 : Graphing Polynomial Functions

Which of the graphs best represents the following function?

Possible Answers:

Graph_cube_

Graph_line_

None of these

Graph_parabola_

Graph_exponential_

Correct answer:

Graph_parabola_

Explanation:

The highest exponent of the variable term is two (). This tells that this function is quadratic, meaning that it is a parabola.

The graph below will be the answer, as it shows a parabolic curve.

Graph_parabola_

Example Question #2 : Graphing Polynomial Functions

Turns on a polynomial graph. 

 

What is the maximum number of turns the graph of the below polynomial function could have? 

Possible Answers:

7 turns

3 turns

4 turns

8 turns

Correct answer:

7 turns

Explanation:

When determining the maximum number of turns a polynomial function might have, one must remember: 

Max Number of Turns for Polynomial Function = degree - 1

First, we must find the degree, in order to determine the degree we must put the polynomial in standard form, which means organize the exponents in decreasing order: 

Now that f(x) is in standard form, the degree is the largest exponent, which is 8. 

We now plug this into the above: 

Max Number of Turns for Polynomial Function = degree - 1

Max Number of Turns for Polynomial Function = 8 - 1 

which is 7. 

The correct answer is 7. 

Example Question #3 : Graphing Polynomial Functions

End Behavior

Determine the end behavior for  below: 

 

     

Possible Answers:

Correct answer:

Explanation:

In order to determine the end behavior of a polynomial function, it must first be rewritten in standard form. Standard form means that the function begins with the variable with the largest exponent and then ends with the constant or variable with the smallest exponent. 

For f(x) in this case, it would be rewritten in this way: 

When this is done, we can see that the function is an Even (degree, 4) Negative (leading coefficent, -3) which means that both sides of the graph go down infinitely. 

In order to answer questions of this nature, one must remember the four ways that all polynomial graphs can look: 

Even Positive: 

Even Negative: 

Odd Positive: 

Odd Negative: 

 

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