\[g(x) = 2x - \frac{1}{3}x^{2};\ \]
\[g( - 1) = 2 \cdot ( - 1) - \frac{1}{3} \cdot ( - 1)^{2} =\]
\[= - 2 + \frac{1}{3} = - 1\frac{2}{3}.\]