Algebra II : Factoring Polynomials

Study concepts, example questions & explanations for Algebra II

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Example Questions

Example Question #101 : Factoring Polynomials

Factor:  

Possible Answers:

Correct answer:

Explanation:

To factor this polynomial, first take a common factor of negative one in order to change the coefficient of  to positive.

Factor the terms inside the parentheses.

The possible factors of the last term, 42, that will provide the middle term   are .

Factorize the polynomial.

Distribute the negative one through the first binomial.

The answer is:  

Example Question #102 : Factoring Polynomials

Find the zeros of the function f(x) where...

Possible Answers:

Correct answer:

Explanation:

The easiest way to solve this problem is to factor the original function, and then to find the zeroes from the factored form. To do this, we start with the original function, f(x). 

Next, we need to set up the function in factored form, leaving blanks for the numbers we don't yet know.

At this point, we need to find two numbers - one for each blank. By looking at the original function, we can gather a few clues that will help us find the two numbers. The product of these two numbers will be equal to the last term of our original function (-14, or c in the standard quadratic formula), and their sum will be equal to the coefficient of the second term of our original function (-5, or b in the standard quadratic formula). Because their product is negative (-14), that must mean that they have different signs - otherwise, their product would be positive. Also, because their sum is negative (-5), we know that the larger of the two numbers must be negative, otherwise their sum would be positive. 

Now, at this point, we may need to test a few different possibilities, using the clues we gathered from the original function. In the end, we'll find that the only numbers that work here are 2 and -7, as the product of 2 and -7 is -14, and sum of 2 and -7 is -5. So, this results in our function's factored form looking like...

Now, the final step in this problem is finding the zeros. To do this, we need to think about what a zero is. A zero is the x-value(s) at which...

So, to solve for our zeros, we just need to set the right side of our function equal to zero and solve for x. 

Because if either of these two factors is equal to zero, the entire function will be equal to zero (as anything multiplied by zero is zero), we can consider each of the two factors separately and solve for x. We'll start with the factor on the left.

We'll finish with the factor from the right.

Now, we have both of our zeros and the answer to our problem...

 

Example Question #103 : Factoring Polynomials

Find the zeros of the function q(x) where...

Possible Answers:

None of the other answers

Correct answer:

Explanation:

The easiest way to solve this problem is to factor the original function, and then to find the zeroes from the factored form. To do this, we start with the original function, f(x). 

Next, we need to set up the function in factored form, leaving blanks for the numbers we don't yet know.

At this point, we need to find two numbers - one for each blank. By looking at the original function, we can gather a few clues that will help us find the two numbers. The product of these two numbers will be equal to the last term of our original function (24, or c in the standard quadratic formula), and their sum will be equal to the coefficient of the second term of our original function (11, or b in the standard quadratic formula). Because their product is positive (24), that must mean that they have the same signs - otherwise, their product would be negative. Also, because their sum is positive (11), and we already know their signs are the same because their product is positive, we know that their signs must both be positive, as the sum of two negative numbers is negative.

Now, at this point, we may need to test a few different possibilities using the clues we gathered from the original function to guide our testing. In the end, we'll find that the only numbers that work here are 3 and 8, as the product of 3 and 8 is 24, and sum of 3 and 8 is 11. So, this results in our function's factored form looking like...

Now, the final step in this problem is finding the zeros. To do this, we need to think about what a zero is. A zero is the x-value(s) at which...

So, to solve for our zeros, we just need to set the right side of our function equal to zero and solve for x. 

Because if either of these two factors is equal to zero, the entire function will be equal to zero (as anything multiplied by zero is zero), we can consider each of the two factors separately and solve for x. We'll start with the factor on the left.

We'll finish with the factor from the right.

Now, we have both of our zeros and the answer to our problem...

 

Example Question #104 : Factoring Polynomials

Find the zeros of the function g(x) where...

Possible Answers:

Correct answer:

Explanation:

The easiest way to solve this problem is to factor the original function, and then to find the zeroes from the factored form. To do this, we start with the original function, f(x). 

Next, we need to set up the function in factored form, leaving blanks for the numbers we don't yet know.

At this point, we need to find two numbers - one for each blank. By looking at the original function, we can gather a few clues that will help us find the two numbers. The product of these two numbers will be equal to the last term of our original function (-36, or c in the standard quadratic formula), and their sum will be equal to the coefficient of the second term of our original function (5, or b in the standard quadratic formula). Because their product is negative (-36), that must mean that they have different signs - otherwise, their product would be positive. Also, because their sum is positive (5), we know that the larger of the two numbers must be positive, otherwise their sum would be negative. 

Now, at this point, we may need to test a few different possibilities, using the clues we gathered from the original function to guide us. In the end, we'll find that the only numbers that work here are 9 and -4, as the product of 9 and -4 is -36, and sum of 9 and -4 is 5. So, this results in our function's factored form looking like...

Now, the final step in this problem is finding the zeros. To do this, we need to think about what a zero is. A zero is the x-value(s) at which...

So, to solve for our zeros, we just need to set the right side of our function equal to zero and solve for x. 

Because if either of these two factors is equal to zero, the entire function will be equal to zero (as anything multiplied by zero is zero), we can consider each of the two factors separately and solve for x. We'll start with the factor on the left.

We'll finish with the factor from the right.

Now, we have both of our zeros and the answer to our problem...

 

Example Question #105 : Factoring Polynomials

Find the zeros of f(x) where...

Possible Answers:

None of the other answers

Correct answer:

Explanation:

The simplest way to solve this problem is to identify that it is a difference of two perfect squares. Recall that the factors of  are  and . Looking back at our original function, we can see that both of our terms are perfect squares -  is a perfect square because  and  is a perfect square because . Therefore, we can treat  as , meaning that , and  as , meaning that , resulting in the factored form . From here, we solve for the zeros like we would with any factoring problem, by setting the right side of our function equal to zero and solving for x. 

Remember that because if either of these two factors is equal to zero, the entire side is equal to zero (as anything multiplied by zero is still zero), we can evaluate each factor separately and solve for x. 

Therefore...

 

Example Question #106 : Factoring Polynomials

Find the zeros of the function q(x) where...

Possible Answers:

Correct answer:

Explanation:

The simplest way to solve this problem is to recognize that it is a difference of two perfect squares. Recall that the factors of  are  and . Looking back at our original function, we can see that both of our terms are perfect squares -  is a perfect square because  and  is a perfect square because . Therefore, we can treat  as , meaning that , and  as , meaning that , resulting in the factored form . From here, we solve for the zeros like we would with any factoring problem, by setting the right side of our function equal to zero and solving for x. 

Remember that because if either of these two factors is equal to zero, the entire side is equal to zero (as anything multiplied by zero is still zero), we can evaluate each factor separately and solve for x. 

Therefore...

Example Question #107 : Factoring Polynomials

Factor:

Possible Answers:

Correct answer:

Explanation:

The first step in solving this problem is to factor as many  as possible from the original expression. This can be seen below.

Next, we can see that inside of the parentheses we have a typical polynomial in the quadratic form that can be factored just like any quadratic. This step is seen below.

This is our final answer, because there is nothing left to factor out. 

Example Question #108 : Factoring Polynomials

Factor:  

Possible Answers:

Correct answer:

Explanation:

In order to factor this, we will need to determine the multiples of the first and last terms.

Using trial and error, and the rule of the FOIL method:

Only  and  will provide us the middle term since:

Substitute the correct values into the binomials.

The answer is:  

Example Question #109 : Factoring Polynomials

Factor:  

Possible Answers:

Correct answer:

Explanation:

In order to factor this, we will first need to pull a negative 1 out as the common factor.

Factor the term in the parentheses.

The factors of the first term are:

The factors of the last term are: 

Using trial and error, we can determine that the factors  for the  term and  for the number 14 will work since the numbers can be manipulated to achieve the middle term.

Remember to add the negative sign in front of the binomials.

The answer is:  

Example Question #110 : Factoring Polynomials

Factor .

Possible Answers:

Correct answer:

Explanation:

First, we notice that there's an  in both the first two terms, and a  in the last two terms, so let's factor those out:

Now we can see a  in both terms, so let's factor that out as well:

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