a, Ta có : \(x^2-16-4xy+4y^2\)
\(=\left(x-2y\right)^2-16\)
\(=\left(x-2y+4\right)\left(x-2y-4\right)\)
b, Ta có : \(x^3-x^2y-xy^2+y^3\)
\(=\left(x+y\right)\left(x^2-xy+y^2\right)-xy\left(x+y\right)\)
\(=\left(x+y\right)\left(x^2-xy+y^2-xy\right)\)
\(=\left(x+y\right)\left(x-y\right)^2\)
https://i.imgur.com/Rnt6Zk6.jpg
a. x2-16-4xy+4y2
= (x2-4xy+4y2)-16
= (x-2y)2-42
= (x-2y-4)(x-2y+4)
b. x3-x2y-xy2+y3
= (x+y)(x2-xy+y2)-xy(x+y)
= (x+y)(x2-xy+y2-xy)
= (x+y)(x-y)2
