Solution
= Solution
The function is nonnegative, <measurable>, and even. Direct integration gives
$$
\int_{\mathbb R}e^{-|x|}\,dx=2\int_0^\infty e^{-x}\,dx=2.
$$
Thus \b[it is <integrable>], with <integral> $\boxed{2}$.
= Solution
The function is nonnegative, <measurable>, and even. Direct integration gives
$$
\int_{\mathbb R}e^{-|x|}\,dx=2\int_0^\infty e^{-x}\,dx=2.
$$
Thus \b[it is <integrable>], with <integral> $\boxed{2}$.