Answer:
The given function is a polynomial function.
The degree of the function is 4 and leading co-efficient is -1.
Explanation:
Given function is:
ƒ(x) = –x^3 – x^4 – 9 + 6x
Putting the terms in order of their power.

A polynomial is an algebraic expression which involves only positive integer exponents for the variables.
A polynomial function is of the form:

We can see that the function has no negative exponent. So the given function is a polynomial function.
The degree of a polynomial is the highest exponent of variable involved and leading co-efficient is the co-efficient of the variable with highest power.
Hence,
The given function is a polynomial function.
The degree of the function is 4 and leading co-efficient is -1.