Question

Rút gọn

\(\left(x-y\right)^2+\left(x+y\right)^2-2\left(x-y\right)\left(x+y\right)-4x^2\)

Answer 1

\(\left(x-y\right)^2+\left(x+y\right)^2-2\left(x-y\right)\left(x+y\right)-4x^2\)

\(=\left(x-y-x-y\right)^2-\left(2x\right)^2\)

\(=\left(-2y\right)^2-\left(2x^2\right)\)

\(=4y^2-4x^2\)

Answer 2

\(\left(x-y\right)^2+\left(x+y\right)^2-2\left(x-y\right)\left(x+y\right)-4x^2\)

\(=\left[\left(x-y\right)^2-2\left(x-y\right)\left(x+y\right)+\left(x+y\right)^2\right]-\left(2x\right)^2\)

\(=\left[\left(x-y\right)-\left(x+y\right)\right]^2-\left(2x\right)^2\)

\(=\left(x-y-x-y\right)^2-\left(2x\right)^2\)

\(=\left(-2y\right)^2-\left(2x\right)^2\)

\(=\left(2y\right)^2-\left(2x\right)^2\)

Answer 3

Mình làm tiếp nha, ấn nhầm nút gửi bài

\(=\left(2y+2x\right)\left(2y-2x\right)\)  ( = 4y² - 4x²)