# How do you write 9x^2 – 64 in factored form?

Apr 10, 2018

$\left(3 x + 8\right) \left(3 x - 8\right)$

#### Explanation:

Difference of two squares (DOTS: ${a}^{2} - {b}^{2} = \left(a - b\right) \left(a + b\right)$) comes in handy with these sorts of equations

Apr 10, 2018

You may see that 9 and 64 are both squares.

#### Explanation:

Now we may rewrite as:

$= {3}^{2} {x}^{2} - {8}^{2} = {\left(3 x\right)}^{2} - {8}^{2}$

And the difference of two squares ${A}^{2} - {B}^{2} = \left(A + B\right) \left(A - B\right)$

Or, in this case where A=3x and B=8:

$= \left(3 x + 8\right) \left(3 x - 8\right)$