Question

Să se calculeze suma 1+2²+2³+...+2 la puterea a9a.

Answer 1

 

$\displaystyle\bf\\1+2+2^2+2^3+...+2^9=\\\\=2^0+2^1+2^2+2^3+...+2^9=\frac{2^{9+1}-1}{2-1}=\\\\=\frac{2^{10}-1}{1}=1024-1=\boxed{\bf1023}$