Question

Is 7× 6 × 5 × 4 × 3 × 2 × 1+ 7
a composite number? Justify your answer.
(class 10 CBSE SAMPLE PAPER 2017-18 MATHS)

Answer 1

Answer:

Given,

7 × 6 × 5 × 4 × 3 × 2 × 1 + 7

This can be written as,

=> 7(6 × 5 × 4 × 3 × 2 × 1 + 1)

=> 7 × (720 + 1)

=> 7 × 721 = 7 × 7 × 103

Here, both 7 × 721 both are prime numbers. And we know that product of two prime numbers is a composite number.

Then,

=> 7 × 721 = 5047

By prime factorisation of

5047 = 7 × 7 × 103

Hence, proved.

Answer 2

Answer:

Your answer is in the attachment above.

Have a great day.