If p and r are integers, and p^2 = 18r, then r must be divisible by which of the following?  Choose the correct answer.
A) 2  B) 4  C) 5  D) 7  E) 9
Ans: D   Solution: for p to be an int 18 r must be whole square of a number.   18r= 9*2*r   to make it whole square we need 9   so r can must be divisible by 9y where y is itself a whole square.   so 9 is the ans
<result>E</result>
If p and r are integers, and p^2 = 18r, then r must be divisible by which of the following?