Big Ideas Math Integrated I, 2016
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Big Ideas Math Integrated I, 2016 View details
6. Solving Absolute Value Inequalities
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Exercise 30 Page 92

How do you find the perimeter of a figure?

Absolute Value Inequality: |2*3 + 2(x+1)-4x|≤3
Solution: 5/2 ≤ x ≤ 11/2

Practice makes perfect

Let P_R be the perimeter of the rectangle and P_S be the perimeter of the square. We are told that the difference between the perimeters of the figures is less than or equal to 3. We can write this as an absolute value equation. |P_R-P_S| ≤ 3 We will now find the perimeter of each figure.

Perimeter of Rectangle

The perimeter of a rectangle with length l and width w can be found using the following formula. P=2l+2w We can see from the given diagram that the length of the rectangle is 3 and its width is x+1. Let's substitute these values into the formula.
P=2l+2w
P=2* 3+2( x+1)

Perimeter of Square

The perimeter of a square with side s can be found using the following formula. P=4s We can see from the given diagram that the side of the square is x. Let's substitute this value into the formula.
P=4s
P=4* x
P=4x

Absolute Value Inequality

We can now substitute these expressions into our absolute value inequality. |2*3 + 2(x+1)-4x|≤3 Let's solve this inequality for x.
|2*3 + 2(x+1)-4x|≤3
|6+2(x+1)-4x|≤3
|6+2x+2-4x|≤3
|-2x+8|≤3

Write as Compound Inequality

-3 ≤ -2x+8 ≤ 3

Subtract 8 from each expression

-11 ≤ -2x ≤ -5

Divide each expression by -2 and flip inequality sign

11/2≥ x ≥ 5/2
5/2 ≤ x ≤ 11/2