It seems that you have mistakenly typed the wrong equation which is supposed to be 4x^2 - 20x = 0. So given the correct equation, the factor for this one would be this: 4x(x-5) = 0 So let us check. 4x (x) = 4x^2 4x (-5) = -20x Which makes it 4x^2-20x = 0 I hope this answer helps.