Question

show that the numner 11*13*15*17+17 is acomposit number

Answer 1

composite number is 15

Answer 2

If we just have to prove that it is a composite number then first take 17 common
17( 11*13*15+1), it can be seen that it is having two factors 17 and 1 and now we know that product of (11*13*15) will be odd always and when we will add 1 to product of (11*13*15) it will become even which means (11*13*15+1) is even and it can be divided by 2 now so now this number is having three factors : 1, 2 & 17 and therefore it is not prime hence it is a composite number.