Question

tại sao tổng 2 mũ 2+2 mũ 3+2 mũ 4+ 2 mũ 5 chia hết cho 3?

 

Answer 1

\(2^2+2^3+2^4+2^5=\left(2^2+2^3\right)+\left(2^4+2^5\right)=2^2\left(1+2\right)+2^4\left(1+2\right)=2^2\cdot3+2^4\cdot3\)

\(=3\cdot\left(2^2+2^4\right)⋮3\)

(đpcm)