Question

a and b are two positive integers such that the least prime factor of a is 3 and the least prime factor of b is 5. Then find the least prime factor of [a+b]

Answer 1

Answer:

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

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

Since least prime factor of a is 3, it means that a is an odd number.

So, if a is even then 2 is the 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.

So, the least prime factor of a + b is 2