giúp mình với, thanks nhiềuuuuuu

Bài `4:`

`a)x+ (-5)/12= 4/7 . 14/48`

`x- 5/12=1/6`

`x=1/6 +5/12`

`x=7/12`

Vậy `x=7/12`

`b)x^2 + 9/-25=2/5 :5/8`

`x^2 - 9/25=2/5 .8/5`

`x^2 - 9/25=16/25`

`x^2=16/25 +9/25`

`x^2=1`

`=>[(x=1), (x=-1):}`

Vậy `x in {1; -1}`

`c)(2x+ 3/8) . 7/4=(-21)/32`

`2x+3/8=-21/32 :7/4`

`2x+3/8=-21/32 . 4/7`

`2x+3/8=-3/8`

`2x=-3/8-3/8`

`2x=-3/4`

`x=-3/4 :2`

`x=-3/4 .1/2`

`x=-3/8`

Vậy `x=-3/8`