Question

explain why 3×5×7+7 is a composite number

Answer 1

HEY mate here is your answer

,3*5*7+7
=7(3*5*1+1)
here we get 7,(3*5*1+1)and 1 as its factor...

as it poses more than one factor so it is a composite number.

hope it helps you

Answer 2

Composite number is a number having factors more than 2...

Note : Every Positive number must have at least two ( Not less than 2 ) factors except 1...

We can write 10 = 2 × 5
=> this means that 2 and 5 are the factors of 10
=> 10 have 2 other factors as 1 and 10 itself...
=> So , 10 have 4 factors viz. 1 , 2 , 5 , 10
=> 10 is a composite number

Solution to problem
=================

Let m = 3×5×7+7
= 7 × ( 3 × 5 + 1 ) ( Taking 7 common )
= n × p , say
where n = 7 and p = 3×5+1
=> m have factors n and p
=> m have factors 1 and m also
=> m have factors 1 , m , n and p
=> m have more than 2 factors
=> m is composite number
=> 3×5×7+7 is composite number...