Question 17
The function $f$ is not defined for $x=0,$ but, for all nonzero real numbers $x,$ $$
f(x)+2f\left(\frac1x\right)=3x.
$$ The equation $f(x)=f(-x)$ is satisfied by
f(x)+2f\left(\frac1x\right)=3x.
$$ The equation $f(x)=f(-x)$ is satisfied by