Find F(x) given f(x) is:

(x+2)(x^2`+ 4x + 3)^5

Well my problem is what do I do with the brackets. I tried but I can't get the answer right.

My attempt:

u=(x^2 + 4x + 3)

u'=2x+4

u^5

u^6/6 + C

(x^2 + 4x + 3)^6/6 + C

I should have 12 instead of 6 on the bottom.

Answer should be:

(x^2 + 4x + 3)^6/12 + C

Thank you