Algebra II
posted by Carlos .
A rectangle is 5 inches wide and 6 inches long. If each side is increased by x, the area is tripled. What is the value of x?

(5+x)(6+x) = 3*30 = 90
30 + 11 x + x^2 = 90
x^2 + 11 x  60 = 0
(x+15)(x4) = 0
x = 4
check
9*10 = 3*30 yes