Question

The dimensions of a rectangle can be expressed as X-1 and x+7. If the area of the rectangle is 128 square inches, find the dimensions of the rectangle.

Answer 1

We have that the area is given by the equation

$\begin{gathered} (x-\text{ 1)( x + 7) = 128} \\ x^2-x\text{ + 7x -7 = 128} \\ x^2+6x\text{ - 135 = 0} \\ (x\text{ - 9)(x +15) = 0 } \end{gathered}$

So we have that x = 9 or x = -15, then we have that taking the positive x = 9.