Answer: 16n^2+16n+3
Steps:
I used the foil method:
(3n+1)(4n+1) = 12n^2+3n+4n+1
(n+2)(4n+1) = 4n^2+n+8n+2
Now combine like terms:
12n^2 + 4n^2 = 16n^2
3n + 4n + n + 8n = 16n
1 + 2 = 3
Put them together:
16n^2 + 16n + 3
Since there's nothing each variable has in common, that's the simplest answer you can get.