Question

a+a^2+...a^2007/a^-1+a^-2+...a^-2007

Answer 1

 
 $frac{a+a^2+a^3+...+a^{2007}}{frac{1}{a}+frac{1}{a^2}+....+frac{1}{a^{2007}}} \ S_{geom} =frac{1}{a}+...frac{1}{a^{2007}} \ b_{1}=frac{1}{a}\ q=frac{1}{a}\ n=2007\ S_{geom} = frac{1-frac{1}{a^{2007}}}{a-1} \ S_{geom} = a+a^2+a^3+...+a^{2007} = frac{a(1-a^{2007})}{1-a}\ frac{frac{a(1-a^{2007})}{1-a}}{frac{1-frac{1}{a^{2007}}}{a-1}} = a^{2008}$   
 
 Ответ  $a^{2008}$