a+a2

The expression "a + a2" can be simplified further depending on the context. If you meant "a + a^2" (where a2 is interpreted as a raised to the power of 2), then it can be written as:

\[ a + a^2 \]

This expression is already simplified, but you might want to factor it:

\[ a + a^2 = a(1 + a) \]

If you meant something different by "a2," could you please clarify?