find the height of a rectangle

Question

the length of a rectangle is 3 less than twice it’s height. if the area is 90, find the height. 

Answer 1

Let h be height and length be L = length. The problem says L = 2h - 3.  So, h * (2h - 3) = 90

 

2h^2 - 3h - 90 = 0.

 

Use quadratic formula to solve for h.