Question

Chứng minh: (7¹⁹⁹⁶ + 7¹⁹⁹⁵ +7¹⁹⁹⁴ ) chia hết cho 399

Answer 1

Ta có : \(7^{1996}+7^{1995}+7^{1994}\) 

\(=7^{1995}\left(7+7^2+7^3\right)\)

\(=7^{1995}.399\)chia hết cho 399 (đpcm)

Answer 2

\(7^{1996}+7^{1995}+7^{1994}\)

\(=7^{1994}\left(7^2+7+1\right)\)

\(=7^{1994}.57\)

\(=7^{1993}.7.57\)

\(=7^{1993}.399\) \(\)chia hết cho 399 (đpcm)