Question

1+2+2^2+2^3+2^4+...+2^50+2^51 bằng nhiu ạ ???

Answer 1

\(S=1+2+2^2+...+2^{50}\)

\(\Leftrightarrow 2S=2+2^2+...+2^{50}+2^{51}\)

\(\Leftrightarrow 2S-S=(2+2^2+...+2^{50}+2^{51})-(2+2^2+...+2^{50}+2^{50})\)

\(\Leftrightarrow S=2^{51}-1\)

_Chúc bạn học tốt_