`a)`\(P=x^2-xy-x+xy^2-y^3-y^2+5\)
\(P=\left(x^2-y^2\right)+y^2\left(x-y\right)-xy-x+5\)
\(P=\left(x-y\right)\left(x+y\right)+y^2-xy-x+5\)
\(P=x+y+y^2-xy-x+5\)
\(P=y-y\left(x-y\right)+5\)
\(P=5\) ( là 1 hằng số )
`b)`\(Q=x^3-x^2y-x^2+xy-x^2+x+5x-5y-2015\)
\(Q=x^2\left(x-y\right)-x\left(x-y\right)-x^2+x+5\left(x-y\right)-2015\)
\(Q=x^2-x-x^2+x+5-2015\)
\(Q=-2010\) ( là 1 hằng số )