Question 1171583: The length of a rectangle is 7 less than the width. The area is 30. Find the dimensions, then find the perimeter. Answer by ikleyn(52778) (Show Source):
ANSWER. The dimensions are 3 units (the length) and 10 units (the width). The perimeter is 3 + 10 + 3 + 10 = 26 units.
Solution
x*(x+7) = 30
x^2 + 7x - 30 = 0
(x-3)*(x+10) = 0
The roots are 3 and -10, and only positive root works.
It is 3 units, the width.
Solved.
The solution can be guessed mentally in 2 seconds.
