Answer:
Correct option: Third one
Step-by-step explanation:
A polynomial is an expression in the form:
[tex]ax^n + bx^{n-1}+...+mx^1+n[/tex]
Where n is a non-negative integer number, and a, b, ... are real coefficients.
The first option is not a polynomial, because there is a non-integer number (5/2) in the exponent of y.
The second option is not a polynomial, because there is a negative integer number in the exponent (the fraction [tex]\frac{1}{x^2}[/tex] is the same as [tex]x^{-2}[/tex], and [tex]\frac{1}{5x}[/tex] is the same as [tex]0.2x^{-1}[/tex]).
The third option is a polynomial, because all numbers in exponent are non-negative integers.
The fourth option is not a polynomial, because there is a variable x in the exponent, so we don't know if the exponent is a non-negative integer number.
