Tìm x biết cho các biểu thức sau

`a)(2x+1)^2-3(2x-12)=(4+2x)^2`

`⇔4x^2+4x+1-6x+36=16+16x+4x^2`

`⇔18x=21`

`⇔x=7/6`

Vậy `S={7/6}`

`b)(4x-3)(5x+2)=2(10x-6)`

 `⇔20x^2-7x-6=20x-12`

`⇔20x^2-27x+6=0`

`⇔20(x^2-27/20x+3/10)=0`

`⇔x^2-27/20x+3/10=0`

`⇔x^2-2 . 27/40x +(27/40)^2-249/1600=0`

`⇔(x-27/40)^2=249/1600`

`⇔x-27/40=±sqrt(249)/40`

`⇔x=±sqrt(249)/40+27/40`

Vậy `S={±sqrt(249)/40+27/40}`