Question

[Minh Anh]

Giúp em với, em đg cần thực sự gấp ạ!!!

Answer 1

[ILoveMath]

Bài 1:

a) \(\left(2x+y\right)^2-\left(y-2x\right)^2=\left(2x+y-y+2x\right)\left(2x+y+y-2x\right)=8xy\)

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

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

d) \(\left(y-\dfrac{1}{2}\right)\left(y+\dfrac{1}{2}\right)=y^2-\dfrac{1}{4}\)

Answer 2

[Nguyễn Lê Phước Thịnh]

Bài 1: 

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

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

=8xy

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

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

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

\(=4x^2\)

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

d: \(\left(y-\dfrac{1}{2}\right)\left(y+\dfrac{1}{2}\right)=y^2-\dfrac{1}{4}\)