Question

simplify (a-b) (a^2+ab+b^2)+ (a+b) (a^2-ab+b^2)

Answer 1

$\sf{\left(a-b\right)\left(a^2+ab+b^2\right)+\left(a+b\right)\left(a^2-ab+b^2\right)}$

$\sf{=a^3-b^3+\left(a+b\right)\left(a^2-ab+b^2\right)}$

$\sf{=a^3-b^3+a^3+b^3}$

$\sf{=a^3+a^3-b^3+b^3}$

$\sf{=2a^3-b^3+b^3}$

$\large\boxed{\sf{=2a^3}}$