`a)4(x+2)-5x=3x-1`
`⇔4x+8-5x=3x-1`
`⇔4x-5x-3x=-1-8`
`⇔-4x=-9`
`⇔x=9/4`
Vậy `S={9/4}`
`b)`
ĐKXĐ:`x\ne-1;x\ne2`
`2/(x+1)+1/(2-x)=(3x-11)/((x+1)(x-2))`
`⇔(2(x-2))/((x+1)(x-2))+(-1(x+1))/((x+1)(x-2))=(3x-11)/((x+1)(x-2))`
`⇒2x-4-x-1=3x-11`
`⇔2x-x-3x=-11+1+4`
`⇔-2x=-6`
`⇔x=3(TM)`
Vậy `S={3}`
`c)(2x+1)/3≥2+(5x-1)/2`
`⇔(4x+2)/6≥(12)/6+(15x-3)/6`
`⇔4x+2≥12+15x-3`
`⇔4x-15x≥12-3-2`
`⇔-11x≥7`
`⇔x≤-7/(11)`
Vậy BPT có tập nghiệm `S={x|x≤-7/11}`
`d)|x+3|-3x=-1`
`⇔|x+3|=-1+3x`
`|x+3|=``{(x+3 nếu x\ge -3),(),(-x-3 nếu x<-3):}`
Xét TH:`x≥-3`
`x+3=-1+3x`
`⇔x-3x=-1-3`
`⇔-2x=-4`
`⇔x=2(tm)`
Xét TH:`x<-3`
`-x-3=-1+3x`
`⇔-x-3x=-1+3`
`⇔-4x=2`
`⇔x=-1/2(loại)`
Vậy pt đã cho có nghiệm:`x=2`
