Đáp án:
$\dfrac{2x-5}{x-2}$ $-$ $\dfrac{3x-5}{x-1}$ $= -1$ (điều kiện $x$$\neq$ $1; x$$\neq$ $2$)
$⇔ (2x-5)(x-1)-(3x-5)(x-2)=-(x-2)(x-1)$
$⇔ 2x²-2x-5x+5-(3x²-6x-5x+10)=-(x²-x-2x+2)$
$⇔ 2x²-2x-5x+5-3x²+6x+5x-10=-x²+x+2x-2$
$⇔ 2x²-3x²+x²-2x-5x+6x+5x-x-2x+5-10+2=0$
$⇔ x-3=0$
$⇔ x=3$ (nhận)
Vậy $S=${$3$}
BẠN THAM KHẢO NHA!!!