$\text{Đáp án + Giải thích các bước giải:}$
`a//9x+4=1-6x`
`<=>9x+6x=-4+1`
`<=>15x=-3`
`<=>x=-(1)/(5)`
$\text{Vậy}$ `S={-(1)/(5)}`
`b//(1)/(x+2)+(1)/(x-2)=(6)/(x^{2}-4)` `(ĐKXĐ:x\ne±2)`
`<=>(x-2)/((x+2)(x-2))+(x+2)/((x-2)(x+2))=(6)/((x-2)(x+2))`
`=>x-2+x+2=6`
`<=>2x=6`
`<=>x=3(TM)`
$\text{Vậy}$ `S={3}`
`c//(x+4)/(x-4)-(1)/(x)=(4)/(x^{2}-4x)` `(ĐKXĐ:x\ne{0;4})`
`<=>(x(x+4))/(x(x-4))-(x-4)/(x(x-4))=(4)/(x(x-4))`
`=>x(x+4)-(x-4)=4`
`<=>x^{2}+4x-x+4-4=0`
`<=>x^{2}+3x=0`
`<=>x(x+3)=0`
`⇔` \(\left[ \begin{array}{l}x=0\\x+3=0\end{array} \right.\)
`⇔` \(\left[ \begin{array}{l}x=0(KTM)\\x=-3(TM)\end{array} \right.\)
$\text{Vậy}$ `S={-3}`
