(2x + 3) chia hết cho (x - 1) (5x - 1) chia hết cho (x + 3) (3x + 2) chia hết cho (2x - 7)

`a) 2x + 3 \vdots x - 1`

`    x - 1 \vdots x - 1`

`=> [(2x + 3) - 2(x - 1)] \vdots x - 1`

`=> [(2x + 3) - (2x - 2)] \vdots x - 1`

`=> 5 \vdots x - 1`

`=> x - 1 in Ư(5) = {1; -1; 5; -5}`

`=> x - 1 in {1; -1; 5; -5}`

`=> x in {2; 0; 6; -4}`

Vậy `x in {2; 0; 6; -4}`

`b) 5x - 1 \vdots x + 3`

`    x + 3 \vdots x + 3`

`=> [(5x - 1) - 5(x + 3)] \vdots x + 3`

`=> [(5x - 1) - (5x + 13) \vdots x + 3`

`=> -14 \vdots x + 3`

`=> x + 3 in Ư(-14) = {1; -1; 2; -2; 7; -7; 14; -14}`

`=> x + 3 in {1; -1; 2; -2; 7; -7; 14; -14}`

`=> x in {-2; -4; -1; -5; 4; -10; 11; -17}`

Vậy ` x in {-2; -4; -1; -5; 4; -10; 11; -17}`

`c) 3x + 2 \vdots 2x - 7`

`    2x - 7 \vdots 2x - 7`

`=> [2(3x + 2) - 3(2x - 7)] \vdots 2x - 7`

`=> [(6x + 4) - (6x - 21)] \vdots 2x - 7`

`=> 25 \vdots 2x - 7`

`=> 2x - 7 in Ư(25) = {1; -1; 5; -5; 25; -25}`

`=> 2x - 7 in {1; -1; 5; -5; 25; -25}`

`=> 2x in {8; 6; 12; 2; 32; -18}`

`=> x in {4; 3; 6; 1; 18; -9}`

Vậy `x in {4; 3; 6; 1; 18; -9}`