Question

CMR \((x+y)(x^2-xy+y^2)=x^3+y^3\)

Answer 1

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

Answer 2

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

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

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

`= x^3 + y^3 (đpcm)`