Question

A = ( 5 + 5 mũ 2 + 5 mũ 3 + .... + 5 mũ 99 + 5 mũ 100 ) chia hết cho 6

Answer 1

mình biết làm nhưng trả lời dài lắm

Answer 2

\(A=5+5^2+5^3+...+5^{99}+5^{100}\)

\(=\left(5+5^2\right)+\left(5^3+5^4\right)+...+\left(5^{99}+5^{100}\right)\)

\(=5\left(1+5\right)+5^3\left(1+5\right)+...+5^{99}\left(1+5\right)\)

\(=5.6+5^3.6+...+5^{99}.6\)

\(=6.\left(5+5^3+...+5^{99}\right)\)

Vì \(A=6.\left(5+5^3+...+5^{99}\right)\)lên A chia hết cho 6.

Answer 3

thanks you