Question

[Trần Nguyễn Hoàng An]

Cho A=\(2^{2011}+2^{2012}+2^{2013}+2^{2014}+2^{2015}+2^{2016}\).Chứng tỏ rằng \(_⋮\)21

Answer 1

[Khánh Phạm Gia]

\(A=2^{2011}+2^{2012}+2^{2013}+2^{2014}+2^{2015}+2^{2016}\)

\(A=2^{2011}.\left(1+2+2^2+2^3+2^4+2^5\right)\)

\(A=2^{2011}.63=2^{2011}.3.21⋮21\)