Question

(x-2y)^2-(x+y)^2

Answer 1

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

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

\(=3y^2-6xy\)

Answer 2

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

\(=\left(2x+y-2\right)\left(-3y\right)\)