.
= 440.
With my magic lamp, I will show you how to solve it mentally.
Multiply by 2 both sides
x*(2x+4) = 880.
Multiply by 2 both sides ONE MORE TIME. You will get
2x*(2x+4) = 1760.
Now find MENTALLY (= guess) decomposition of the number 1760 into product of two factors, that differ by 4.
To faculitate guessing, recall that is about 40, or slightly more than 40.
Taking it into account, you find this decomposition in 1 second
1760 = 40*44.
Thus 2x = 40, x = 40/2 = 20.
It is your ANSWER: the base of the triangle is 20 inches.
Solved.
So, lazy person can solve it mentally . . .