Question

The area of the rectangle is 80 square inches. the length of the rectangle is (2x) inches and width is (x-3).what is the value of X?

Answer 1

  A = lw
80 = 2x(x - 3)
80 = 2x(x) - 2x(3)
80 = 2x² - 6x
  0 = 2x² - 6x - 80
  0 = 2(x²) - 2(3x) - 2(40)
  0 = 2(x² - 3x - 40)
  2               2
  0 = x² - 3x - 40
  0 = x² - 8x + 5x - 40
  0 = x(x) - x(8) + 5(x) - 5(8)
  0 = x(x - 8) + 5(x + 8)
  0 = (x + 5)(x + 8)
  0 = x + 5    or    0 = x + 8
- 5        - 5         - 8        - 8
 -5 = x      or      -8 = x

The values of x are -5 and -8.