a million. x^2 - (y - z)^2 i think of the least complicated way of doing those style of questions is to handle them as a term. case in point: enable (y - z) = a So x^2 - (y - z)^2 = x^2 - a^2 = (x-a)(x+a) replace y - z back right into a. = [x-(y-z)][x+(y-z)] = (x - y +z)(x + y - z) Q2. that's corresponding to Q1. enable x = a + 2b (a + 2b)^2 - 9c^2 = x^2 - 9c^2 = (x - 3c)(x + 3c) = [(a+2b) - 3c][(a+2b) + 3c] = (a + 2b - 3c)(a + 2b + 3c)