If $f$ is **odd** on $[-a, a]$, then $\displaystyle\int_{-a}^{a} f(x)\, dx$ equals:
- $0$
- $2\int_0^a f(x)dx$
- $a$
- Cannot be determined
Show answer and solution
Correct answer: A. $0$
By symmetry, odd-function integrals over symmetric intervals vanish.
(For even $f$: $2\int_0^a f$.)