Question

Chứng minh đẳng thức :

a ) ( x2 + y2 )2 – 4x2 y2 = ( x + y ) 2 ( x – y )2

 

Answer 1

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

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