`a) x : 4 1/3 =-2,5`
`x : 13/3 = -5/2`
`x = -5/2 . 13/3`
`x =-65/6`
Vậy `x = -65/6`
``
`b) x : (-3)/5 = (-10)/21`
`x = (-10)/21 . (-3)/5`
`x=2/7`
vậy `x = 2/7`
``
`c)2/3 x - 1/2 =1/10`
`2/3 x = 1/10 + 1/2`
`2/3 x =3/5`
`x = 3/5 : 2/3`
`x=9/10`
Vậy `x = 9/10`
``
`d) 1/3 x + 2/5 ( x - 1) = 0`
`1/3 x + 2/5 x - 2/5 = 0`
`( 1/3 + 2/5) x = 0 + 2/5`
`11/15 x = 2/5`
`x = 2/5 : 11/15`
`x=6/11`
Vậy `x = 6/11`
``
`e) 1/2 x + 1/2 = 5/2`
`1/2 x = 5/2 - 1/2`
`1/2 x = 2`
`x = 2 : 1/2`
`x=4`
Vậy `x=4`
``
`f) (-2)/3 - 1/3 (2x - 5)= 3/2`
`1/3 ( 2x - 5) = (-2)/3 - 3/2`
`1/3 ( 2x - 5) = -13/6`
`(2x - 5) = -13/6 : 1/3`
`2x - 5 =-13/2`
`2x = -13/2 + 5`
`2x = -3/2`
`x = -3/2 : 2`
`x= -3/4`
Vậy `x = -3/4`
``
`g) (3x- 1)( -1/2 x + 5) = 0`
⇒ `+) 3x - 1 = 0`
`3x = 0 + 1`
`3x = 1`
`x = 1 : 3`
`x = 1/3`
`+) -1/2 x + 5 = 0`
`-1/2 x = 0 - 5`
`-1/2 x = -5`
`x = -5 : (-1/2)`
`x= 10`
Vậy `x∈ { 1/3 ; 10}`
``
`h) 3 1/3 + 5/6 x = 3 1/2`
`5/6 x = 3 1/2 - 3 1/3`
`5/6 x = 1/6`
`x = 1/6 : 5/6`
`x= 1/5`
``
`i) 1/4 + 1/3 : (2x - 1) =-5`
`1/3 : ( 2x - 1) = -5 - 1/4`
`1/3 : ( 2x - 1) =-21/4`
`(2x - 1) = 1/3 : (-21/4)`
`2x - 1 =-4/63`
`2x = -4/63 + 1`
`2x = 59/63`
`x = 59/63 : 2`
`x=59/126`
``
`k) | x - 1/2| - 1/4 = 0,75`
`|x - 1/2| = 3/4 + 1/4`
`|x - 1/2 | = 1`
⇒ `+) x - 1/2 = 1`
`x = 1 + 1/2`
`x = 3/2`
`+) x - 1/2 = -1`
`x = -1 + 1/2`
`x = -1/2`
Vậy `x∈ { 3/2 ; -1/2}`
``
