Question

Answer 1

\(VT=\left(xy+1\right)\left(x^2y^2-xy+1\right)+\left(x^3-1\right)\left(1-y^3\right)\)

\(=\left(xy\right)^3+1^3+x^3-x^3y^3-1+y^3\)

\(=\left(x^3y^3-x^3y^3\right)+\left(1-1\right)+x^3+y^3\)

\(=x^3+y^3=VP\)

#\(Toru\)

Answer 2

`(xy +1) (x^2y^2 -xy+1) +(x^3-1)(1-y^3)`

`= x^3y^3 - x^2y^2 +xy +x^2y^2 -xy+1 + x^3 -x^3y^3 -1+y^3`

`= (x^3y^3 -x^3y^3) +(-x^2y^2+x^2y^2) +(xy-xy) +x^3+y^3`

`=x^+y^3(đpcm)`