-Đáp án+Giải thích các bước giải:
`a) (x-1)^2-(x-1)(x+1)=3x-5`
`⇔ (x-1)(x-1-x-1)=3x-5`
`⇔ -2.(x-1) =3x-5`
`⇔ -2x+2=3x-5`
`⇔ -5x = -7`
`⇔ x = 7/5`
Vậy`S={7/5}`
`b) x/(x+11)+3/(x-12)=(-12x+33)/((x+11)(x-12)) (ĐKXĐ:x\ne-11, x\ne 12)`
`⇔ (x(x-12))/((x+11)(x-12))+(3(x+11))/((x+11)(x-12))=(-12x+33)/((x+11)(x-12))`
`⇒ x^2 - 12x +3x+33= -12x+33`
`⇔ x^2 +3x=0`
`⇔ x(x+3)=0`
`⇔`\(\left[ \begin{matrix}x=0\\x+3=0\end{matrix} \right.\)
`⇔`\(\left[ \begin{matrix}x=0(t/m)\\x=-3(t/m)\end{matrix} \right.\)
Vậy `S={0; -3}`
