S=[2+2^2+2^3]+[2^4+2^5+2^6]+...+[2^2008+2^2009+2^2010] CHIA HẾT CHO 14
SUY RA S CHIA HẾT CHO 14
GIỮ LỜI NHA
S = 2 + 22 + 23 + ... + 22010
= (2 + 22 + 23) + (24 + 25 + 26) + ... + (22008 + 22009 + 22010)
= 2(1 + 2 + 22) + 24(1 + 2 + 22) + ... + 22008(1 + 2 + 22)
= 2.7 + 24.7 + ... + 22008. 7
= 14 + 23.14 + ... + 22007.14
= 14(1 + 23 + ... + 22007) \(⋮\)14
\(S=2+2^2+2^3+...+2^{2010}\)
\(=\left(2+2^2+2^3\right)+2^3\left(2+2^2+2^3\right)+...+2^{2007}\left(2+2^2+2^3\right)\)
\(=\left(2+2^2+2^3\right)\left(1+2^3+2^6+...+2^{2007}\right)\)
\(=14\left(1+2^3+...+2^{2007}\right)⋮14\left(dpcm\right)\)
