Question

\(4x^2+4x+1=x^2\)

Answer 1

\(4x^2+4x+1=x^2\)

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

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

=>\(x+1=0=>x=-1\)

hoặc \(3x+1=0=>x=\dfrac{-1}{3}\)

Answer 2

`4x^2+4x+1=x^2`

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

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

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

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

Vậy `S={-1/3 ; -1}`.