\(y = 1 - 2x - 3x^2\)

At maximum point, \(\frac{\mathrm d y}{\mathrm d x} = 0\)

\(\frac{\mathrm d y}{\mathrm d x} = -2 - 6x\)

\(-2 - 6x = 0 \implies -2 = 6x\)

\(x = -\frac{1}{3}\)

At x = \(-\frac{1}{3}\), y = \(1 - 2(-\frac{1}{3}) - 3(-\frac{1}{3})^{2}\)

= \(1 + \frac{2}{3} - \frac{1}{3}\)

= \(\frac{4}{3}\)