\[x^{2} - 2(p - 1)x + 4p^{2} = 0\]
\[D_{1} = (p - 1)^{2} - 4p^{2} =\]
\[= p^{2} - 2p + 1 - 4p^{2} =\]
\[= - 3p^{2} - 2p + 1.\]
\[При\ D = 0\ уравнение\ имеет\ \]
\[одно\ решение:\]
\[- 3p^{2} - 2p + 1 = 0\]
\[3p^{2} + 2p - 1 = 0\]
\[D_{1} = 1 + 3 = 4\]
\[p_{1} = \frac{- 1 + 2}{3} = \frac{1}{3};\]
\[p_{2} = \frac{- 1 - 2}{3} = - 1.\]
\[Ответ:при\ p = - 1;p = \frac{1}{3}.\]