`1,` `T=x^3-2x^2-xy^2+2xy+10x+10y`
`⇒T=(x^3-xy^2)-(2x^2-2xy)+(10x+10y)`
`⇒T=x(x^2-y^2)-2x(x-y)+10(x+y)`
`⇒T=x(x^2-y^2)-2x(x-y)+10(x+y)`
`⇒T=x[(x^2-xy)+(xy-y^2)]-2x(x-y)+20`
`⇒T=x[x(x-y)+y(x-y)]-2x(x-y)+20`
`⇒T=x(x+y)(x-y)-2x(x-y)+20`
`⇒T=x.2.(x-y)-2x(x-y)+20`
`⇒T=20`