`a, 2x-5=x+3`
`⇔2x-x=5+3`
`⇔x=8`
`Vậy S={8}`
`b, 3-x=4-2x `
`⇔-x+2x=-3+4`
`⇔x=1`
`Vậy S={1}`
$c)\dfrac{ x}{3-x}=\dfrac{x+1}{2}$
`MC:2(3-x)`
`ĐKXĐ:xne3`
$⇔\dfrac{ 2x}{2(3-x)}=\dfrac{(x+1)(3-x)}{2(3-x)}$
`⇒2x=3x-x^2+3-x`
`⇔2x-3x+x+x^2=3`
`⇔x^2=3`
`⇔x=√3≈1,7(nhận)`
`Vậy S={1,7}`
$d) x-3=\dfrac{6}{x-3}$
`MC:x-3`
`ĐKXĐ:xne3`
⇔$\dfrac{(x-3)^2}{x-3}=\dfrac{6}{x-3}$
`⇒(x-3)^2=6`
`⇔(x-3)^2-6=0`
`⇔(x-3)^2-(√6)²=0`
`⇔(x-3+√6)(x-3-√6)=0`
⇔$\left \{ {{x-3+√6=0} \atop {x-3-√6=0}} \right.$
⇔$\left \{ {{x=3-√6} \atop {x=3+√6}} \right.$
⇔$\left \{ {{x≈0,6(nhận)} \atop {x≈5,4(nhận)}} \right.$
`Vậy S={0,6;5,4}`
