The difference of squares will factor into conjugates like this:
[tex]\rm a^2-b^2\quad=\quad (a-b)(a+b)[/tex]
In order to apply this property,
we must first write both terms as perfect squares.
36 is 6^2, that's easy enough to rewrite as a perfect square.
The other one is a little trickier.
16 is 4^2. From there we'll group the 4^2 and x^2 into a single square using an exponent property,
[tex]\rm 16x^2=4^2x^2=(4x)^2[/tex]
So our expression looks like this,
[tex]\rm 16x^2-36[/tex]
[tex]\rm (4x)^2-6^2[/tex]
Applying our difference of squares rule,
[tex]\rm (4x)^2-6^2=(4x-6)(4x+6)[/tex]
Hope that helps! :)
