Question

dear sir/madame,

Solve using identities (a-b)(a square +b square) - ( a+b)(a square + b square - ab).

Answer 1

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

=a^3-b^3-(a^3+b^3)

=a^3-b^3-a^3-b^3
= -2b^3