Question

help

Answer 1

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

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

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

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

\(=-2y^3\)