Question 84583
(a^2 + 2ab - b^2)(a^2 - 7ab + b^2)

= a^4 - 7a^3b + a^2b^2 + 2a^3b - 14a^2b^2 + 2ab^3 - a^2b^2 + 7ab^3 - b^4

I'll pass it onto you now.