Question

cứu b

Answer 1

7⁶+7⁵-7⁴ ⋮ 55

=>7⁴.(7²+7-1)=7⁴.55 ⋮ 55

=>7⁶+7⁵-7⁴ ⋮ 55

Answer 2

`7^6+7^5-7^4`

`=7^4 . 7^2+7^4 . 7-7^4 . 1`

`=7^4(7^2+7-1)`

`=7^4(49+6)`

`=7^4 . 55``\vdots``55`

Vậy `7^6+7^5-7^4``\vdots``55`