Which expression is equal to 9/√45?

A. 3√3 / 5

B. 3√5 / 5

C. √5

D. 3√3

B)

Step-by-step explanation:

Because sqrt (45) = sqrt (9*5) = sqrt (9) * sqrt (5) = 3*sqrt (5) and you have 9 / (3*sqrt (5)). But you need to simplify this further because 9/3 gives you 3, so you have 3/sqrt (5). Since most answer choices won't have sqrt (5) for the denominator, you need to multiply sqrt (5) by the numerator and the denominator in order to get rid of the radicals. Therefore, the answer is B).