Answer
It is a polynomial.
Degree: 4
Leading term: $4x^4$
Constant: 0
Standard form: $4x^4+5x^2$
Work Step by Step
By definition, a polynomial is a function containing only terms where x is raised to a power or constants. x is raised to the fourth power, and x is raised to the second power in the term $5x^2$, so we see that it is a polynomial. The degree is equal to the exponent of the term with the highest exponent, so the degree is 4. The term that has the highest degree, $4x^4$, is always the leading term. Finally, there are no constants listed, so the constant is 0.
