Most of them are polynomials.
A polynomial cannot contain any denominator or roots that contain a
variable. However, polynomials may contain denominators and roots as
long as they do not contain any variables.
4, 8, and 9 are not polynomials because they contain denominators that
contain variables.
The others are polynomials except that I can't tell about 7. It depends on
whether you meant
It would have been good if you had written parentheses to group together
what goes inside the square root, like this: √(2)x+4, √(2x)+4, or √(2x+4)
The first one's root does not contain x, so it's a polynomial.
The other two's's roots do, so they're not polynomials.
Edwin