We are given two numbers and and are asked to explain wthether they are composite. Let us consider the first number . We have;
We take 13 common in the above step to have;
We see that except one and the number itself 7×11×13+137×11×13+13 has two more factors 13 and 78. Since now it has more than two factors 7×11×13+137×11×13+13 is a composite number. Let us consider the second number. We have;
We take 5 common in the above step to have;
So, the statement is true.