Question

4. Explain why 7 x 11 x 13 + 13 and
7x6x5 x 4x3x2x1 + 5 are composite
numbers. AP June '16 (AS)​

Answer 1

Answer:

Yes! it is a composite no. because it has more than two prime factor.

Step-by-step explanation:

7 x 11 x 13 + 13

We can also write this as

⇒ (77 + 1) x 13

⇒ 1014

So the factors are

⇒ 13 x 13 x 3 x 2

It is a composite number. The given number has more than two factors.

Now consider

7 x 6 x 5 x 4 x 3 x 2 x 1 + 5

We can also write it as

⇒ 5(7 x 6 x 5 x 4 x 3 x 2 x 1 + 1)

By calculation we get

⇒ 1009 x 5

It is a composite number. The given number has more than two factors.

Hence proved.

Hope it helps you!!