Question

(a + b)(a - 2b)

Answer 1

a^2-2ab+ab-2b^2

Answer 2

FOIL method
F - first
O - outside
I - inside
L - last
(a + b)(a - 2b)
First - multiply first terms in each set....a * a = a^2
Outside - multiply outside terms ....a * -2b = -2ab
Inside - multiply inside terms ...b * a = ab
Last - multiply last terms....b * -2b = -2b^2
Now put them together...
a^2 - 2ab + ab - 2b^2 (combine like terms)
a^2 - ab - 2b^2