McGraw Hill Integrated II, 2012
MH
McGraw Hill Integrated II, 2012 View details
8. Differences of Squares
Continue to next subchapter

Exercise 73 Page 63

Factor the given equation. Then use the Zero Product Property to solve it.

{6, 16}

Practice makes perfect

To solve the given equation we will factor it and then apply the Zero Product Property.

Factoring

Let's start by rewriting the equation in such way that all the terms are on the left side of the equality sign. 22x-x^2=96 ⇕ 22x-x^2-96=0 To make the process of factoring easier, let's rearrange the order of the terms in such way that they follow the standard form of a quadratic function. 22x-x^2-96=0 ⇕ - x^2+22x-96=0 To completely factor the given expression, we will now rewrite the expression as a trinomial with a leading coefficient of 1.

- x^2+22x-96 = - (x^2-22x+96) Now, to factor a trinomial with a leading coefficient of 1, think of the process as multiplying two binomials in reverse. Let's take a look at the constant term. - (x^2-22x+ 96)=0 In this case, we have 96. This is a positive number, so for the product of the constant terms in the factors to be positive, these constants must have the same sign (both positive or both negative.)

Factor Constants Product of Constants
1 and 96 96
-1 and - 96 96
2 and 48 96
-2 and - 48 96
3 and 32 96
-3 and - 32 96
4 and 24 96
-4 and - 24 96
6 and 16 96
-6 and - 16 96
8 and 12 96
-8 and - 12 96

Next, let's consider the coefficient of the linear term. -(x^2 -22x+ 96)=0 For this term, we need the sum of the factors that produced the constant term to equal the coefficient of the linear term, - 22.

Factors Sum of Factors
1 and 96 97
-1 and - 96 - 97
2 and 48 50
-2 and - 48 - 50
3 and 32 35
-3 and - 32 - 35
4 and 24 28
-4 and - 24 - 28
6 and 16 22
-6 and - 16 - 22
8 and 12 20
-8 and - 12 - 20

We found the factors whose product is 96 and whose sum is - 22. - (x^2 -22x+ 96)=0 ⇕ - (x-6)(x-16)=0

Solving the Equation

Now, as we have already factored the equation, we can apply the Zero Product Property to solve it.
- (x-6)(x-16)=0
lcx-6=0 & (I) x-16=0 & (II)
lx=6 x-16=0
lx=6 x=16
We found that the solutions of the given equation are x=6 and x=16.

Checking the Answer

We can substitute our solutions back into the given equation and simplify to check if our answers are correct. We will start with x=6.
22x-x^2=96
22( 6)- 6^2? =96
â–Ľ
Simplify
22(6)-36? =96
132-36? =96
96=96 âś“
Substituting and simplifying created a true statement, so we know that x=6 is a solution of the equation. Let's move on to x=16.
22x-x^2=96
22( 16)- 16^2? =96
â–Ľ
Simplify
22(16)-256? =96
352-256? =96
96=96 âś“
Again, we created a true statement. x=16 is indeed a solution of the equation.