Question

(3ab)(-5ab) i need to know how to do it

Answer 1

foil

Answer 2

-15ab^2

Answer 3

foil thanks much

Answer 4

Multiply the common things adding the exponents.
\[(3ab)(-5ab)=(3)(-5)(a^1)(a^1)(b^1)(b^1)=-15a^{1+1}b^{1+1}=-15a^2b^2\]