Answer
$\bf True$.
Work Step by Step
$\bf True$.
Because $y(x)^{4}\geq 0$ for all $x$, we know that $-1-y^{4}$ is strictly negative for all values of $x$. Hence, this means that $y'$ is strictly negative for all $x$ . By the first derivative test , this means that $y$ is decreasing.
