Factorise fully 42x cubed + 6x

First, we can factor out the greatest common factor 6x:

42x^3 + 6x = 6x(7x^2 + 1)

This expression is already fully factorised as (7x^2 + 1) cannot be factorised any further.

Decrease 3680 by 15%

To decrease 3680 by 15%, we need to find 15% of 3680 and then subtract it from 3680.

15% of 3680 can be calculated as:

(15/100) x 3680 = 552

So, to decrease 3680 by 15%, we need to subtract 552 from it:

3680 - 552 = 3128

Therefore, the answer is 3128.

To factorize 42x^3 + 6x fully, we need to identify any common factors that can be extracted. In this case, we can factor out a common factor of 6x from both terms:

42x^3 + 6x = 6x(7x^2 + 1)

Therefore, the fully factorized form of 42x^3 + 6x is 6x(7x^2 + 1).