y is odd, x^3*y^4=5000, what is y?
1) x is integer
2) y > 0
First, break this down into the prime factors:
5, 5, 5, 5, 2, 2, 2
1) Since we know that x is an integer, then y, which is an odd integer, can be either 5 or -5. X must be 2. Insufficient
2) This statement doesn't tell us that x must be an integer, so Y could be any odd number. Insufficient
Together, we know that x=2 and y=5.
The answer is C.