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1)if least prime factor of `a' is 3 and least prime factor of `b' is 7,then the least prime factor of (a+b) is _______________

a) 2 b) 3 c) 5 d) 11
i want ans in a clear manner then only i will pick as best


Lets first talk about a since on prime factorisation it yeilds 3 as least prime no.,all other prime factors must be odd only since 2 is not there the resulting no. will be an odd no.( product of odds=odd) Similarly in b 7 is the least prime no. So it must be an odd no. Sum of two odd no. is even i.e (a+b) is even . So its prime factor (least) is 2
1 5 1
i problem way i want
I didn't understand
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