gaokao 2023 Q4

gaokao · China · national-B-science Composite & Inverse Functions Symmetry, Periodicity, and Parity from Composition Conditions

Given that $f ( x ) = \frac { x e ^ { x } } { e ^ { a x } - 1 }$ is an even function, then $a =$
A. $- 2$
B. $- 1$
C. 1
D. 2

Given that $f ( x ) = \frac { x e ^ { x } } { e ^ { a x } - 1 }$ is an even function, then $a =$\\
A. $- 2$\\
B. $- 1$\\
C. 1\\
D. 2