Answer
polynomial, $n=4$,
$f(x)=4x^4+5x^2$, $4x^4$, $0$.
Work Step by Step
Step 1. Given $f(x)=5x^2+4x^4$, we can determine it is a polynomial function.
Step 2. We can identify the degree as $n=4$.
Step 3. In standard form $f(x)=4x^4+5x^2$. We can identify the leading term as $4x^4$ and the constant term as $0$.