Math Help - fractions

1. fractions

Could I get some hints for the attached problem?

Thanks.

2. Re: fractions

If we make substitution : $x=2009$ we can write :

$\frac {(x+3)(x+1)(x-1)(x-3)-9}{(x+5)(x+1)(x-1)(x-5)+135}=\frac {x^4-10x^2}{x^4-26x^2+160}=\frac {x^4-10x^2}{x^4-16x^2-10x^2+160}=$

$=\frac{x^2(x^2-10)}{x^2(x^2-16)-10(x^2-16)}=\frac{x^2}{x^2-16}=\frac {2009^2}{2009^2-4^2}=\frac{2009^2}{2005 \cdot 2013}$