Question

Chứng minh rằng: 2 + 2 mũ 2 + 2 mũ 3 + 2 mũ 4 +......+ 2 mũ 59 + 2 mũ 60 chia hết cho 3.

Answer 1

\(2+2^2+2^3+2^4+...+2^{59}+2^{60}\\ =\left(2+2^2\right)+\left(2^3+2^4\right)+...+\left(2^{59}+2^{60}\right)\\ =2\left(1+2\right)+2^3\left(1+2\right)+...+2^{59}\left(1+2\right)\\ =\left(1+2\right)\left(2+2^3+...+2^{59}\right)\\ =3\left(2+2^3+...+2^{59}\right)⋮3\)