Сократите дробь: ((a+1)^2+(a-1)^2)/(3a^2+3).

\[\frac{(a + 1)^{2} + (a - 1)^{2}}{3a^{2} + 3} =\]

\[= \frac{a^{2} + 2a + 1 + a^{2} - 2a + 1}{3 \cdot \left( a^{2} + 1 \right)} =\]

\[= \frac{2a^{2} + 2}{3 \cdot \left( a^{2} + 1 \right)} =\]

\[= \frac{2 \cdot (a^{2} + 1)}{3 \cdot (a^{2} + 1)} = \frac{2}{3}\]