\[x^{2} - (a + 3)x + 2a + 2 = 0\]
\[D = (a + 3)^{2} - 4 \cdot 1 \cdot (2a + 2) =\]
\[= a^{2} + 6a + 9 - 8a - 8 =\]
\[= a^{2} - 2a + 1 = (a - 1)^{2}\]
\[x_{1,2} = \frac{a + 3 \pm \sqrt{(a - 1)^{2}}}{2} =\]
\[= \frac{a + 3 \pm |a - 1|}{2}\]
\[1.\ При\ D = 0:\ \ \]
\[(a - 1)^{2} = 0\]
\[a - 1 = 0\ \ \]
\[a = 1.\]
\[x = \frac{1 + 3 \pm 0}{2} =\]
\[= \frac{4}{2} = 2 - не\ подходит.\]
\[2.\ При\ \ a \neq 1:\]
\[x_{1} = \frac{a + 3 + a - 1}{2} =\]
\[= \frac{2a + 2}{2} = a + 1;\]
\[x_{2} = \frac{a + 3 - a + 1}{2} =\]
\[= \frac{4}{2} = 2 - не\ подходит.\]