McGraw Hill Integrated II, 2012
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McGraw Hill Integrated II, 2012 View details
6. Solving x^2+bx+c=0
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Exercise 11 Page 49

Use factoring to find the amount of reduction.

8 inches by 12 inches

Practice makes perfect

We start by writing an equation using the information. Afterwards, we will rewrite it in standard form. Then, we will use factoring to solve it.

Writing Equation

Tina wants to reduce the width and the length of the photo by the same amount so that the area of the smaller photo is half of the original area.

After she resizes the photo, the width and the length will be x inches shorter. w= 12-x & l = 16-x Since the area is reduced to half the original area, we can write the equation below. ( 12-x)( 16-x) = 12 * 16/2 ⇕ (12-x)(16-x)= 96

Rewriting Equation

To find the new dimensions, we need to solve for x. Before that, we will rewrite the equation in standard form.

(12-x)(16-x)=96
192-12x-16x+x^2=96
192-28x+x^2=96
96-28x+x^2=0
x^2-28x+96=0

Factoring

Now, we will use factoring.

x^2-28x+96=0
x^2-4x-24x+96=0
â–¼
Factor out x & (- 24)
x(x-4)-24x+96=0
x(x-4)-24(x-4)=0
(x-24)(x-4)=0

Solving

To solve this equation, we will apply the Zero Product Property.

(x-24)(x-4)=0
lcx-24=0 & (I) x-4=0 & (II)
lx=24 x-4=0
lx_1=24 x_2=4

Let's substitute the solutions and find possible dimensions.

w=12-x l = 16-x
x=24 w=12-24= - 12 l = 16-24= - 8
x=4 w=12-4= 8 l = 16-4= 12

Since dimensions cannot be negative, the new photo is 8 inches by 12 inches.

Checking Our Answer

Checking Our Answer
Let's check if the area of the new photo is equal to half the original area. w=8 & l=12 Their product is equal to 96, half the original area. 8 * 12 =96 ✓