Giải thích các bước giải:
`a)`
`|x-1|=8`
`<=>`\(\left[ \begin{array}{l}x-1=8\\x-1=-8\end{array} \right.\)
`<=>`\(\left[ \begin{array}{l}x=8+1=9\\x=-8+1=-7\end{array} \right.\)
Vậy `S={-7;9}`
`b)`
`x(2+x)-3=0`
`⇔x^2+2x-3=0`
`⇔x^2+3x-x-3=0`
`<=>x(x+3)-(x+3)=0`
`<=>(x-1).(x+3)=0`
`<=>`\(\left[ \begin{array}{l}x-1=0\\x+3=0\end{array} \right.\)
`<=>`\(\left[ \begin{array}{l}x=1\\x=-3\end{array} \right.\)
Vậy `S={-3;1}`
_______________________________________
`b)`
`x(2+x)-3=0`
`⇔x^2+2x-3=0`
Ta có: `a+b+c=1+2-3=0`
`=>x_1=1;x_2=(c)/(a)=-3`
Vậy `S={-3;1}`
