`a):`
`2x + 3 \vdots x`
`⇒ 2x \vdots x`
`⇒ 3 \vdots x`
`⇒ x in` Ư`(3)`
`x in {1; 3}`
`b):`
`8x + 4 \vdots 2x - 1`
`⇒ 4(2x - 1) + 8 \vdots 2x - 1`
`⇒ 4(2x - 1) \vdots 2x - 1`
`⇒ 8 \vdots 2x - 1`
`⇒ 2x - 1 in` Ư`(8)`
`⇒ 2x - 1 in {-8; -4; -2; -1; 1; 2; 4; 8}`
`⇒ 2x in {-7; -3; -1; 0; 2; 3; 5; 9}`
`x in {0; 1}`
`c):`
`x^2 - x + 5x + 1 \vdots x - 1`
`⇒ x^2 - 5x + 7 \vdots x - 5`
`⇒ x - 5 in` Ư`(7)`
`⇒ x - 5 in {+- 1; +- 7}`
`⇒ x - 5 = 1; x = 1 + 5 = 6`
`⇒ x - 5 = -1; x = -1 + 5 = 4`
`⇒ x - 5 = 7; x = 7 + 5 = 12`
`⇒ x - 5 = -7; x = -7 + 5 = 2`
`x in {6; 4; 12; 2}`
Cho mình xin hay nhất nha bạn!!!!
@Drew Mclntyre