Phân tích thành nhân tử: (x + y)^2 – (x – y)^2
Giải thích
x+y2 – x-y2 = [(x + y) + (x – y)][(x + y) – (x – y)]
= (x + y + x – y)(x + y – x + y) = 2x.2y = 4xy
x+y2 – x-y2 = [(x + y) + (x – y)][(x + y) – (x – y)]
= (x + y + x – y)(x + y – x + y) = 2x.2y = 4xy