$\text{Đáp án + Giải thích các bước giải:}$
`(x-4)/(x(x+2))-(1)/(x(x-2))=(-2)/((x+2)(x-2))` `(ĐKXĐ:x\ne{±2;0})`
`<=>((x-4)(x-2))/(x(x+2)(x-2))-(x+2)/(x(x-2)(x+2))=(-2x)/(x(x+2)(x-2))`
`=>(x-4)(x-2)-(x+2)=-2x`
`<=>x^{2}-4x-2x+8-x-2=-2x`
`<=>x^{2}-7x+6=-2x`
`<=>x^{2}-7x+2x+6=0`
`<=>x^{2}-5x+6=0`
`<=>(x^{2}-3x)-(2x-6)=0`
`<=>x(x-3)-2(x-3)=0`
`<=>(x-3)(x-2)=0`
`<=>` \(\left[ \begin{array}{l}x-3=0\\x-2=0\end{array} \right.\)
`<=>` \(\left[ \begin{array}{l}x=3(TM)\\x=2(KTM)\end{array} \right.\)
`\text{Vậy}` `S={3}`
