Answer:
C
Explanation:
Comment
The square root of 48 is nowhere near 12. That means that A and D are wrong. On a test that's an important consideration because if you have to guess, you've just cut the possibilities down to 2.
So the answer must be B or C. Furthermore, you don't have to go to the trouble of factoring 48 to show that it is 4 sqrt(3). There's no other choice.
So what about x^5. 5 is an odd number. That means that one of the xs is left underneath the square root sign. That makes B incorrect. Without doing a calculation, I know that C is the answer.
Note
x^5 = x * x * x * x * x
The rule is for ever 2 factors that are the same, 1 factor is put in front of the square root sign and the other 1 is thrown out.
√x^5 = √x * x * x * x * x = x * x √x
Therefore the answer to the problem is 4 x * x√3 x = 4x^2√3x