\(\Leftrightarrow4x^2-12x+9-4=0\)
\(\Leftrightarrow4\left(x^2-3x+\frac{9}{4}\right)=4\)
\(\Leftrightarrow\left(x-\frac{3}{2}\right)^2=1\)
\(\Leftrightarrow\left[{}\begin{matrix}x-\frac{3}{2}=1\\x-\frac{3}{2}=-1\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=-\frac{5}{2}\\x=-\frac{1}{2}\end{matrix}\right.\)
có viết thiếu ở chỗ 12x ko bạn