How would you multiply a binomial by a trinomial?

Step-by-step explanation:

Multiply one of them by each of the terms in the other, then distribute. Finally, combine like terms.

(ax + b) (cx² + dx + e)

ax (cx² + dx + e) + b (cx² + dx + e)

acx³ + adx² + aex + bcx² + bdx + be

acx³ + (ad+bc) x² + (ae+bd) x + be