How do you evaluate #(2b - 3) ( b + 3)#?

1 Answer
Oct 13, 2017

#=\2b^2+3b-9#

Explanation:

To multiply two binomials (basically the things in parentheses), we use the idea of FOIL. FOIL stands for First, Outer, Inner, Last. We add each of these products to get the final answer. Let's run through this.

First: Multiply the first term of each binomial.

#2b*b=2b^2#

Outer: Multiply the two outer terms.

#2b*3=6b#

Inner: multiply the two inner terms.

#(-3)*b=-3b#

Note that I kept the sign of the #3# in this product.

Last: multiply the last term of each binomial.

#(-3)*3=-9#

Now, we add up the four terms we got:

#2b^2+6b+(-3b)+(-9)#

#=2b^2+3b-9#