`a)3x-5=5x-1`
`⇔3x-5x=-1+5`
`⇔-2x=4`
`⇔x=4:(-2)`
`⇔x=-2`
Vậy `S={-2}`
`b)5x-2=3x+1`
`⇔5x-3x=1+2`
`⇔2x=3`
`⇔x=3/2`
Vậy `S={3/2}`
`c)4(x+3)=-7x+17`
`⇔4x+12=-7x+17`
`⇔4x+7x=17-12`
`⇔11x=5`
`⇔x=5/11`
Vậy `S={5/11}`
`d)5(x-3)-4=2(x-1)+7`
`⇔5x-15-4=2x-2+7`
`⇔5x-19=2x+5`
`⇔5x-2x=5+19`
`⇔3x=24`
`⇔x=24:3`
`⇔x=8`
Vậy `S={8}`
`e)(x+1)(x+9)=(x+3)(x+5)`
`⇔x²+9x+x+9=x²+5x+3x+15`
`⇔x²+10x+9=x²+8x+15`
`⇔x²+10x-x²-8x=15-9`
`⇔2x=6`
`⇔x=6:2`
`⇔x=3`
Vậy `S={3}`
`f)(x+1)(2x-3)-3(x-2)=2(x-1)²`
`⇔2x²-3x+2x-3-3x+6=2(x²-2x+1)`
`⇔2x²+(-3x+2x-3x)+(-3+6)=2x²-4x+2`
`⇔2x²-4x+3=2x²-4x+2`
`⇔2x²-4x-2x²+4x=2-3`
`⇔0x=-1(vô lý)`
Vậy `S=∅`
