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

1 Answer
Zachary
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.

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