Answer:
A, B, C and E are polynomial functions, D is not.
Step-by-step explanation:
An polynomial is an algebraic entity of the form:
![p(x) = \Sigma \limits_{i=0}^{n}\, a_{i}\cdot x^{i}, \forall i\in\mathbb{N}_{O}](https://tex.z-dn.net/?f=p%28x%29%20%3D%20%5CSigma%20%5Climits_%7Bi%3D0%7D%5E%7Bn%7D%5C%2C%20a_%7Bi%7D%5Ccdot%20x%5E%7Bi%7D%2C%20%5Cforall%20i%5Cin%5Cmathbb%7BN%7D_%7BO%7D)
Where
is the i-th coefficient and
is the order of the polynomial.
The function A is a third-order polynomial.
The function B is a second-order polynomial.
The function C is a third-order polynomial.
The function D is not a polynomial due to the presence of a square root.
The function E is a fourth-order polynomial.