Calculate x in Rectangular Area Equation: 2(x-4) by 2x+8 Yields 132

Question

The area of the rectangle below is 132.

Calculate x.

2(x-4)2(x-4)2(x-4)2x+82x+82x+8

Video Solution

Solution Steps

00:00 Find X
00:03 Use the formula for calculating rectangle area (side times side)
00:09 Substitute the side values according to the given data
00:19 Substitute the area size according to the given data and solve for X
00:30 Open parentheses properly
00:38 Use the shortened multiplication formulas to expand the parentheses
00:59 Calculate 2 squared and 8 squared
01:06 Isolate X
01:23 Take the square root to find the possible solutions for X
01:29 And this is the solution to the problem

Step-by-Step Solution

To solve the problem, let's proceed with the following steps:

  • Step 1: Identify the area formula
  • Step 2: Substitute side expressions
  • Step 3: Simplify the equation and solve

Let's begin:
Step 1: The area of the rectangle is given by the formula:
Area=Length×Width \text{Area} = \text{Length} \times \text{Width} For this rectangle, the length and width are given as 2x+8 2x + 8 and 2(x4) 2(x-4) , respectively. Thus, we have the equation for the area:

(2x+8)×(2(x4))=132 (2x + 8) \times (2(x - 4)) = 132

Step 2: Substitute the side expressions and set up the equation:

(2x+8)×(2x8)=132 (2x + 8) \times (2x - 8) = 132

Step 3: Expand and solve:

  • First, we expand the expression using multiplication:
  • The side expression simplifies to a difference of squares:
(2x+8)(2x8)=(2x)282 (2x + 8)(2x - 8) = (2x)^2 - 8^2 =4x264 = 4x^2 - 64

The area equation is:

4x264=132 4x^2 - 64 = 132

Step 4: Simplify and solve the quadratic equation:

  • Add 64 64 to both sides to isolate the quadratic term:
  • 4x2=196 4x^2 = 196
  • Divide by 4 4 :
  • x2=49 x^2 = 49
  • Take the square root:
  • x=±49 x = \pm \sqrt{49} x=±7 x = \pm 7

Therefore, the solutions for x x are x=7 x = 7 and x=7 x = -7 . Since area is scalar, both positive and negative solutions are valid for x x .

Thus, the correct value for x x is ±7 \pm 7 .

Answer

±7 \pm7