\(3x^2+4x-4=0\)
\(\Leftrightarrow3x^2+6x-2x-4=0\)
\(\Leftrightarrow\left(3x^2+6x\right)-\left(2x+4\right)=0\)
\(\Leftrightarrow3x\left(x+2\right)-2\left(x+2\right)=0\)
\(\Leftrightarrow\left(x+2\right)\left(3x-2\right)=0\)
\(\Leftrightarrow\orbr{\begin{cases}x+2=0\\3x-2=0\end{cases}\Leftrightarrow\orbr{\begin{cases}x=-2\\x=\frac{2}{3}\end{cases}}}\)