Question

làm ơn giúp em với

chứng tỏ rằng:

M=3¹+3³+.....................+3²⁰¹⁵ chia hết cho 70

làm ơn giúp em đi,em sẽ tick cho,nha  nha nha

Answer 1

\(M=3^1+3^3+....+3^{2015}\)

\(M=\left(3^1+3^3+3^5+3^7+3^9+3^{11}\right)+......+\left(3^{2005}+3^{2007}+3^{2009}+3^{2011}+3^{2013}+3^{2015}\right)\)

\(M=\left(3^1+3^3+3^5+3^7+3^9+3^{11}\right)+....+3^{2004}.\left(3^1+3^3+3^5+3^7+3^9+3^{11}\right)\)

\(M=199290+......+3^{2004}.199290\)

MÀ \(199290⋮70\)

\(\Rightarrow M=199290+.....+2^{2004}.199290⋮70\)

HAY \(M=3^1+3^3+......+3^{2015}⋮70\left(đpcm\right)\)

Answer 2

cảm ơn bn rất nhiều