Tìm số nguyên x sao cho : 5x + 7 chia hết cho x - 2

1 câu trả lời

`5x + 7 \vdots x - 2`

`x - 2 \vdots x - 2`

`=> [(5x + 7) - 5(x - 2)] \vdots x - 2`

`=> [(5x + 7) - (5x - 10)] \vdots x - 2`

`=> 17 \vdots x - 2`

`=> x - 2 in Ư(17) = {1; -1; 17; -17}`

`=> x - 2 in {1; -1; 17; -17}`

`=> x in {3; 1; 19; -15}`

Vậy `x in {3; 1; 19; -15}`