Question

分解因式 4-12(x-y)+9(x-y)^2

Answer 1

(a+b)^2 = a^2 + 2ab + b^2

a = 2,b = 3(x-y)

所以,上式可以写成：

4 - 12(x-y) + 9(x-y)^2

=[2 - 3(x-y)]^2