A rectangle is 6 cm long and 5 cm wide. When each dimension is increased by x cm, the area is tripled. Find the value of x.

Answer 1

(6+x)(5+x) = 3*(6*5)
x^2 + 11x + 30 = 90
x^2 + 11x - 60 = 0
(x+15)(x-4) = 0
x = 4 -- we like positive dimensions

check: (6+4)(5+4) = 90 = 3*30