The problem wants me to use the quotient rule and this is the problem

d/dx 3x^2 + 3/ arctanx

I can get the answer worked out as far as

6xarctanx - (3x^2 + 3) ( 1 / (x^2 + 1) / arctan^2 x

but the final answer in the book is

6xarctanx - 3/ arctan^2 x

how does it go from what I have to what the final answer should be? I figure it something simple but I just am not seeing it.