which expression is not a polynomial?

[tex]x^{2}[/tex]-[tex]\sqrt{x}[/tex]+2 is not a Polynomial,This one is a radical term.
Explanation:
A polynomial can own:
That can be joined utilizing the four operations (+,-,*,/)
So: A polynomial can have, variables, constants, and exponents,
but a variable can divide.
Also, they can have one or more terms, but not an endless number of cycles.
vx is not, because the exponent is "½" (see fractional exponents).