Question

s=2 la puterea 1 + 2 la puterea 2 +...+ 2 la puterea 40 =??

Answer 1

[tex]S=2+2^2+2^3+...+2^{40}|(-2)\\ -2S=-2^2-2^3...-2^{41}\\ ......................................\\ S-2S=2-2^{41}\\ -S=2-2^{41}\\ S=2^{41}-2[/tex]