\[2x^{2} - (2k + 1)x + k = 0\]
\[D = (2k + 1)^{2} - 4 \cdot 2 \cdot k =\]
\[= 4k^{2} + 4k + 1 - 8k =\]
\[= 4k^{2} - 4k + 1 = (2k - 1)^{2}\]
\[k \neq \frac{1}{2} \Longrightarrow D > 0:\]
\[x_{1} = \frac{2k + 1 + 2k - 1}{2 \cdot 2} = \frac{4k}{4} = k\]
\[x_{2} = \frac{2k + 1 - (2k - 1)}{2 \cdot 2} =\]
\[= \frac{2k + 1 - 2k + 1}{4} = \frac{2}{4} = \frac{1}{2}.\]
\[k = \frac{1}{2} \Longrightarrow D = 0:\]
\[x = \frac{2k + 1}{2 \cdot 2} = \frac{2 \cdot \frac{1}{2} + 1}{4} =\]
\[= \frac{1 + 1}{4} = \frac{2}{4} = \frac{1}{2}.\]
\[Ответ:x = k\ и\ \ x = 0,5\ \ при\ \]
\[k \neq 0,5;\ \ \]
\[\ \ \ \ \ \ \ \ \ \ \ \ \ \ x = 0,5\ \ при\ \ k = 0,5.\]