Question

solve by multiplying (a+b)(a^3-3ab-b^2)

Answer 1

Multiply term-by-term:

(a+b)(a^3 - 3ab - b^2)
= a(a^3 - 3ab - b^2) + b(a^3 - 3ab - b^2)
= a^4 - 3a^2b - ab^2 + a^3b - 3ab^2 - b^3.

Combine like terms (the ab^2 terms):

= a^4 + a^3b - 3a^2b - 4ab^2 - b^3.