Question

If 3 is the least prime factor of number a and 7 is the least prime factor of number b, then the least prime factor of (a + b) is (a) 2 (b) 3 d) 10 If a = 2 is equal to​

Answer 1

Answer:

Correct option is

A

2

It is given that 3 is the least prime factor of number a and 7 is the least prime factor of number b. Therefore, a should be greater than or equal to 3 and b should be greater than or equal to 7.

That is a≥31 and b≥71

Now, consider the case a=3 and b=7

Then, a+b=3+7=10

Then, 2 is the least prime factor of a+b.

Let us consider the case a=32=9 and b=72=49

So, it is clear that a+b=58 which is an even number.

Similarly, for the value of n,an+bn is divisible by 2.

Hence, the least prime factor of a+b is 2.