Question

explain why 7×11×13+13 and 7×6×5×4×3×2×1+5 are composite numbers
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Answer 1

Step-by-step explanation:

Composite numbers are all natural numbers that are not prime numbers since they can be divided by more than two numbers.

Exsmple:20(It is divisible by 1,2,4,5,10,20)

Now consider

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.