`a, x : 3/2 = ( - 12 )/5`
`⇔ x = ( - 12 )/5 xx 3/2`
`⇔ x = ( - 18 )/5`
Vậy , `x = ( - 18 )/5 .`
`b, ( - 5 )/2 x + 7/3 = 5/6`
`⇔ ( - 5 )/2 x = 5/6 - 7/3`
`⇔ ( - 5 )/2 x = ( - 3 )/2`
`⇔ x = ( - 3 )/2 : ( - 5 )/2`
`⇔ x = 3/5`
Vậy , `x = 3/5 .`
`c, 3/5 + 2/5 . ( 2x - 3 ) = 4 1/5`
`⇔ 3/5 + 2/5 . ( 2x - 3 ) = 21/5`
`⇔ 2/5 . ( 2x - 3 ) = 21/5 - 3/5`
`⇔ 2/5 . ( 2x - 3 ) = 18/5`
`⇔ 2x - 3 = 18/5 : 2/5`
`⇔ 2x - 3 = 9`
`⇔ 2x = 9 + 3`
`⇔ 2x = 12`
`⇔ x = 12 : 2`
`⇔ x = 6`
Vậy , `x = 6 .`
`d, ( 3/4 - x )^2 - 2,5 = 9/16`
`⇔ ( 3/4 - x )^2 - 5/2 = 9/16`
`⇔ ( 3/4 - x )^2 = 9/16 + 5/2`
`⇔ ( 3/4 - x )^2 = 49/16`
Trường hợp `1 : ( 3/4 - x )^2 = ( 7/4 )^2`
`⇔ 3/4 - x = 7/4`
`⇔ x = 3/4 - 7/4`
`⇔ x = - 1`
Trường hợp `2 : ( 3/4 - x )^2 = ( ( - 7 )/4 )^2`
`⇔ 3/4 - x = ( - 7 )/4`
`⇔ x = 3/4 - ( - 7 )/4`
`⇔ x = 5/2`
Vậy , `x ∈ { - 1 ; 5/2 } .`
