Question 113
If x and y are two positive integers, and m is the HCF of x and y such that mxy = 1080 and 3 < m < 12 , then how many possible ordered pairs of x and y exist?
Solution
Factorize 1080 - $$2^3\cdot3^3\cdot5$$. Here, HCF has to be between 3 and 12; the only possible number would be 6. The remaining thing that exists is only 5. So there are two ways: one, 5, belong to x, and two, five, belong to y.
