Question

If a and b are two positive integers such that the least prime factor of a is 3and the least prime factor of b is 5 then calculate the least prime facto(a+b)

Answer 1

Given that, a is a positive integer and 3 is least prime factor of a.

Also, b is a positive integer and 5 is least prime factor of b.

Since least prime factor of a is 3, it implies that 'a' is an odd number [if a is even then 2 is least prime factor of a].

Similarly b is also an odd number.

Now, it is known that sum of two odd numbers is an even number.

Hence, a + b will be an even number.

∴ The least prime factor of a + b is 2.