How do you multiply (3x +2) (3x - 2)?

1 Answer
Mar 24, 2018

9x^2-4
You must distribute the values.

Explanation:

There is a method for this called FOIL. The means First, Outer, Inner, Last.
First-Multiply the first terms in each binomial, meaning 3x*3x. 3*3=9, and x*x=x^2. So the first term is 9x^2.
Outer-Multiply the first term of the first binomial by the outermost term, meaning 3x*-2, which equals -6x.
Inner-Multiply the innermost terms, so 2*3x, which equals 6x. 6x-6x cancels out, so their will be no middle term.
Last-The last terms of each binomial, multiplied, which is 2*-2, which equals -4.

Combine the remaining results, which are just 9x^2 and -4, to make 9x^2-4.

You can check an answer such as this one by substituting an x value and seeing if the expressions are equal.