Algebra (Period 1)

Multiplying Polynomials 5-11

To multiply two polynomials, multiply each term of one polynomial by every term of the other. THEN ADD the results.

The textbook shows a column approach, please see page 249 for instructions.
In class we used the BOX method... and then combined terms.

When you multiply a trinomial by a binomial or two trinomials, it gets really tricky!


2 ways:

1) box method

2)column method
(double or triple distributive with columns to combine like terms)




If you have a trinomial times a binomial, it's easier to use the Commutative Property

and make it a binomial times a trinomial:

(x² + x - 1) (x - 1)

switch it to

(x - 1) (x² + x - 1)

Remember the following rules
(A + B)(A + B) = (A + B) ² = A² + 2AB + B²

(A - B)(A - B) = (A - B)² = A² -2AB + B²

(A + B)(A - B)= A²- B²
You can use FOIL to multiply two binomials
remember FOIL is First Terms, Outside Terms, Inside Terms, Last Terms

You can always use FOIL-- or the BOX method but knowing these rules will make computation quicker if you know the above rules!!