# Algebra II : Polynomial Functions

## Example Questions

### Example Question #11 : Polynomial Functions

Polynomial Functions

Find the -intercepts for the polynomial function  below:

Explanation:

When finding the x-intercepts for a function, this is where the function crosses the x-axis, which means that  or  must equal zero.

So we first set  which gives us:

Now in order to solve this equation, we must break down the polynomial using the "Factor by Grouping" Method.

To "Factor by Grouping" you must put the polynomial in standard form and then group into to pairs of binomials.

After doing this, one can see that there is a common factor in each group.

When an  is taken out of the first pair we are left with  and,

when a  is taken out of the second pair we are left with  again.

The goal is to make each the same and we now have two

This is now a common factor on this side of the equation, so we can take out the common factor  and we get ths result.

We can now find the x-intercepts by remembering that we origianilly set this all equal to 0.

In order for this product to equal zero, either the first or second parentheses needs to equal zero, so we set each equal to zero and solve.

and .

After taking the square root of both sides for  you get .

### Example Question #1081 : Algebra Ii

If , find .

Explanation:

Substitute 5y in for every x:

.

Simplify:

Square the first term:

Distribute the coefficients:

### Example Question #13 : Polynomial Functions

If , find .

Explanation:

Substitute  for  in the original equation:

.

Use FOIL or the Square of a Binomial Rule to find .

Recall that FOIL stands for the multiplication between the First components in both binomials followed by the Outer components, then the Inner components, and lastly the Last components.

Then, Distribute: .

Combine like terms to simplify:

### Example Question #14 : Polynomial Functions

If , find

None of the answers are correct.

Explanation:

To find , substitute  for  in the original equation:

.

Use FOIL or the Square of Binomial Rule to find .

Recall that FOIL stands for the multiplication between the First components in both binomials followed by the Outer components, then the Inner components, and lastly the Last components.

Therefore,

You can then simplify the equation.

Distribute the multiplier:

Combine like terms: .

To find , distribute 3 throughout the equation to get:

Subtract the two expressions:

### Example Question #15 : Polynomial Functions

Find  if

Explanation:

For , substitue for :

.

Use FOIL or square of a binomial to find .

Recall that FOIL stands for the multiplication between the First components in both binomials followed by the Outer components, then the Inner components, and lastly the Last components.

Therefore,

Distribute and combine like terms to simplify:

.

For , first substitute  for :

.

Multiply the entire expression by 3:

.

### Example Question #16 : Polynomial Functions

If , what is ?

Explanation:

To solve this problem, plug in 2p for x in the function: . Then, simplify: .

### Example Question #17 : Polynomial Functions

Let

What is ?

Explanation:

The question asks us to put the expression of  into the expression for  anyplace there is an :

The 2nd power needs to be distributed to both the  and . The first term then becomes:

The final answer is then

### Example Question #18 : Polynomial Functions

If

,

what is

?

Explanation:

To solve this problem, simply plug in 1 wherever you see x.

.

Therefore,

.

### Example Question #19 : Polynomial Functions

Explanation:

To determine the end behavior for a function, we must look at the degree and the sign associated with the function. For this function:

The degree is 6 (the highest power) which is an even number, and the sign is positive (the sign associated with the leading coefficient, which in this case is positive 1).

Taken together, we can see that we have an "even positive" function. Even functions always go the same direction at both extreme ends. Think of a parabola, both sides either both go up or both go down - this is the same for all even functions.

Since this is an even positive; both sides will approach positive infinity.

We express this mathematically when we say that as x approaches negative infinity (left side) the function will approach positive infinity:

....and as x approaches positive infinity (right side) the function again approaches positive infinity.

### Example Question #20 : Polynomial Functions

Determine a possible zero:

Explanation:

Rewrite this equation in order of high to lower powers.

Factor out an x-term  from the equation.  The equation becomes:

Factorize the term inside the parentheses.

Set each individual term equal to zero and solve for .

The zeros are:

One of the possible root is: