Simplify: \aca2+2a+1a2−1\ac{a^2 + 2a + 1}{a^2 - 1}\aca2+2a+1a2−1.
\aca+1a−1\ac{a+1}{a-1}\aca+1a−1
\aca−1a+1\ac{a-1}{a+1}\aca−1a+1
1
a+1a+1a+1