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

Mar 24, 2018

$9 {x}^{2} - 4$
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 $3 x \cdot 3 x$. $3 \cdot 3 = 9$, and $x \cdot x = {x}^{2}$. So the first term is $9 {x}^{2}$.
Outer-Multiply the first term of the first binomial by the outermost term, meaning $3 x \cdot - 2$, which equals $- 6 x$.
Inner-Multiply the innermost terms, so $2 \cdot 3 x$, which equals $6 x$. $6 x - 6 x$ cancels out, so their will be no middle term.
Last-The last terms of each binomial, multiplied, which is $2 \cdot - 2$, which equals $- 4$.

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

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