Which of the following are polynomial

The correct options are C and D.

Step-by-step explanation:

A polynomial expression is an expression where the exponents are whole numbers:

(Where n >= 0)

So, looking at the options, we have:

A. The first term has a negative exponent in x, so it's not a polynomial.

B. The third term has a square root, so it's not a polynomial.

C. This expression is a polynomial.

D. This expression is a polynomial.

E. The third term has x in the denominator, so it's not a polynomial.

Therefore the correct options are C and D.