Question

ai giúp kui bài này vớiiiiiiiiiiii

Answer 1

n: \(=\left(x+y\right)^3+z^3-3xy\left(x+y\right)-3xyz\)

\(=\left(x+y+z\right)\left(x^2+2xy+y^2-xz-yz+z^2\right)-3xy\left(x+y+z\right)\)

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

r: \(=3x^2-3xy+2020xy-2020y^2\)

\(=3x\left(x-y\right)+2020y\left(x-y\right)\)

\(=\left(x-y\right)\left(3x+2020y\right)\)