\(y=3x^2+2x-4 |:3\)
\(\frac{y}{3}=x^2+\frac{2}{3}x-\frac{4}{3} | +\frac{4}{3} \)
\(\frac{y}{3}+\frac{4}{3}=x^2+\frac{2}{3}x | q.E. \)
\(\frac{y}{3}+\frac{4}{3}+(\frac{1}{3})^2=(x+\frac{1}{3})^2 |*3 \)
\(y+4+\frac{1}{3}=3*(x+\frac{1}{3})^2 | -4- \frac{1}{3} \)
\(y=3*(x+\frac{1}{3})^2-\frac{13}{3} \)