Question

(x+1)²=4(x²-2x+1)

Answer 1

\(\left(x+1\right)^2=4\left(x^2-2x+1\right)\)

\(\Leftrightarrow x^2+2x+1-4\left(x^2-2x+1\right)=0\)

\(\Leftrightarrow x^2+2x+1-4x^2+8x-4=0\)

\(\Leftrightarrow-3x^2+10x-3=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x=3\\x=\dfrac{1}{3}\end{matrix}\right.\)

Vậy \(S=\left\{\dfrac{1}{3};3\right\}\)

Answer 2

 `(x+1)^2=4(x^2-2x+1)`

`<=>(x+1)^2-[2(x-1)]^2=0`

`<=>(x+1-2x+2)(x+1+2x-2)=0`

`<=>(-x+3)(3x-1)=0`

`<=>-x+3=0` hoặc `3x-1=0`

`<=>x=3` hoặc `x=1/3`

Vậy `S={1/3;3}`

Answer 3