Question

[Trần Mạnh Quân]

- Rút gọn biểu thức sau:

a) (x + y)² + (x - y)²

b) 2(x - y)(x + y) + (x - y)² + (x + y)²

Answer 1

[Phạm Tuán Quang]

a, \(x^2+2xy+y^2+x^2-2xy+y^2\)

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

b, \(\left(x+y\right)^2+2\left(x-y\right)\left(x+y\right)+\left(x-y\right)^2\)

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

xin tiick

Answer 2

[Phước Lộc]

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

\(=x^2+y^2+2xy+x^2+y^2-2xy\)

\(=2x^2+2y^2\)

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

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

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

\(=2\left(2x^2\right)=4x^2\)