Question

Chứng minh : \(7^6+7^5-7^4⋮11\)

Answer 1

Ta có:

7⁶ + 7⁵ - 7⁴

=7⁴.7²+7⁴.7-7⁴.1

=7⁴.(7²+7-1)

=7⁴.(49+7-1)

=7⁴.55

=7⁴.5.11

Vì 7⁴.5.11\(\) chia hết cho 5

=> ĐPCM

Answer 2

Ta có: \(7^6+7^4-7^4=7^4.\left(7^2+7-1\right)=7^4.55⋮11\)

\(\Rightarrow7^6+7^5-7^4⋮11\left(đpcm\right)\)