Question

If a and b are two positive co-prime integers such that a = 12b, then HCF (a, 12) = ______.

Answer 1

If a and b are two positive co-prime integers such that a = 12b, then HCF (a, 12) = 12.

Explanation:

a = 12b and gcd(a, b) = 1.

But gcd(12b, b) = b, so b = 1 and hence a = 12. 

Therefore HCF(a, 12) = HCF(12, 12) = 12.