I'm not sure why the 36 and 36 become 6x6?

Joshua,

We'll know that the square root of V(16) is 4, because 4 * 4 = 16
When we want to simply V(16) we factor it to prime numbers, which is called factorization.
Thus V(16) can be written as V(2*2*2*2) whenever we end up with two like factors we can 'factor them out' so V(2*2*2*2) becomes 2V(2*2) now we can do the same thing again, 2V(2*2) becomes 4V(1) and the square root of 1 is 1, so 4(1)=4.
In this case we could have done it simpler, from V(2*2*2*2) to V(4*4) and factor the 4 out gives us our final answer 4.
As you might have noticed already a = V(a*a), this means that whenever we'll end up with V(a*a) we immediately can tell the root hence it's a.

In the question we'll end up with V(36*36), so the root is....

Niels

Joshua, let me try a different way because this question is pretty basic.

√(36 x 36)
= √36 x √36, because you can distribute square root in multiplications or divisions
= 6 x 6

Hello everyone, what's goin' on? Sick and tired of not getting a 700 because questions are too frustrating? Well, here's a "walkthrough":
42-6=36 and 20+16=36.
Now we multiply them in the algebraic way so that we yield out 36^2. The "square" simplifies with the square root and we get (E) as our final answer.