Answer
The domain of $ f(x)=\frac{4}{x^4+1}$ is $ R $. Also, the range of $ f(x)$ is $0\lt y\leq 4$.
Work Step by Step
Since $ x^4+1\neq 0$ for all $ x\in R $, then the domain of $ f(x)=\frac{4}{x^4+1}$ is $ R $. Also, the range of $ f(x)$ is $0\lt y\leq 4$.
