Question

CMR A=7⁷⁶+7⁷⁵+7⁷⁴ chia het cho 57

Answer 1

A = 7⁷⁶ + 7⁷⁵ + 7⁷⁴
   = 7⁷⁴(7² + 7 + 1)
   = 7⁷⁴(49 + 7 + 1)
   = 7⁷⁴ . 57

Vậy A chia hết cho 57

Answer 2

\(A=7^{76}+7^{75}+7^{74}=7^{74}\cdot7^2+7^{74}\cdot7+7^{74}=7^{74}\left(7^2+7+1\right)=57\cdot7^{74}⋮57\)