Question

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

Answer 1

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

\(\Leftrightarrow\left(x-1\right)^2=\left(\pm2\right)^2\)

\(\Leftrightarrow\left[{}\begin{matrix}x-1=2\\x-1=-2\end{matrix}\right.\)

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

\(S=\left\{3,-1\right\}\)

Answer 2

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

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

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

\(\left(x-3\right)\left(x+1\right)=0\)

=>\(x-3=0=>x=3\)

hoặc \(x+1=0=>x=-1\)