c) 18 ⁝ x; 12 ⁝ x , x lớn nhất d) 120 : ( 2x - 6) = 12

Lời giải: 

`c) Vì: 18 ⁝ x; 12 ⁝ x`

Nên: `x ∈ UCLN(18,12)`

`18= 2. 3^2`

`12= 2^2 . 3`

`UCLN (18,12)= 2. 3 = 6`

`=> x = 6`

`d) 120 : ( 2x - 6) = 12`

`2x - 6 = 120 : 12`

`2x - 6 = 10`

`2x=10+6`

`2x=16`

`x=16:2`

`x=8`

Vậy: `x=8`

`@Don``na`

`c,`

Ta có:

`18 \vdots x`

`12 \vdots x`

`x` lớn nhất

`=> x in ƯCLN(18, 12)`

`18 = 2 * 3^2`

`12 = 2^2 * 3`

`=> ƯCLN(18, 12) = 2 * 3 = 6`

Vậy `x = 6`

`d, 120 : (2x - 6) = 12`

  `2x - 6 = 120 : 12`

  `2x - 6 = 10`

  `2x = 10 + 6`

  `2x = 16`

  `x = 16 : 2`

  `x = 8`

Vậy `x = 8`