Answer
$\text{odd}$
Work Step by Step
Recall:
a) A function is said to be odd, when every number $x$ in its domain, the number $-x$ is also in the domain such that $f(-x)=-f(x)$
b) A function is said to be even, when every number $x$ in its domain, the number $-x$ is also in the domain such that $f(-x)=f(x)$
Replace in the given function $-x$ for $x$ to evaluate $f(-x)$.
$f(-x)=4(-x^3) \\=-4x^3 \\=-f(x)$
Therefore, the function $f(x)$ is odd.
