Đáp án:
`S={1;1/3}`
Giải thích các bước giải:
`(x+1)^2=4(x^2-2x+1)`
`<=>(x+1)^2=4(x-1)^2`
`<=>(x+1)^2=[2(x-1)]^2`
`<=>(x+1)^2=(2x-2)^2`
`<=>(x+1)^2-(2x-2)^2=0`
`<=>(x+1-2x+2)(x+1+2x-2)=0`
`<=>(3-x)(3x-1)=0`
`<=>` \(\left[ \begin{array}{l}3-x=0\\3x-1=0\end{array} \right.\) `<=>` \(\left[ \begin{array}{l}x=3\\x=\dfrac{1}{3}\end{array} \right.\)
Vậy `S={3;1/3}`
