Đề bài yêu cầu là gì vậy bạn?

Chỉnh đề:

\(S=2+2^2+2^3+2^4+...+2^{10}\)

\(2S=2.\left(2+2^2+2^3+2^4+...+2^{10}\right)\)

\(2S=2^2+2^3+2^4+2^5+...+2^{11}\)

\(2S-S=\left(2^2+2^3+2^4+2^5+...+2^{11}\right)-\left(2+2^2+2^3+2^4+...+2^{10}\right)\)

\(S=2^{11}-2\)

\(#\)\(Wendy\) \(Dang\)

\(Ư\left(20\right)=\left\{\pm1;\pm2;\pm4;\pm5;\pm10;\pm20\right\}\)

\(Ư\left(30\right)=\left\{\pm1;\pm2;\pm3;\pm5;\pm6;\pm10;\pm15;\pm30\right\}\)

\(Ư\left(12\right)=\left\{\pm1;\pm2;\pm3;\pm4;\pm6;\pm12\right\}\)

\(B\left(8\right)=\left\{0;\pm8;\pm16;\pm24;\pm32;\pm40;...\right\}\)

\(Ư\left(45\right)=\left\{\pm1;\pm3;\pm5;\pm9;\pm15;\pm45\right\}\)

\(B\left(7\right)=\left\{0;\pm7;\pm14;\pm21;\pm28;...\right\}\)

\(B\left(5\right)=\left\{0;\pm5;\pm10;\pm15;\pm20;....\right\}\)