Which of the following is a polynomial?
A. (x^6 - 4)/(x^-5 + 1)
B. x^4 - 2
C. x^-x + 2
D. x^-2 - 1
According to Wikipedia, a polynomial is an expression consisting of indeterminates (also called variables) and coefficients, that involves only the operations of addition, subtraction, multiplication, and non-negative integer exponentiation of variables.
The first one is just a mess.
The second one fits all conditions.
The third one has a variable exponent.
The fourth one has a negative exponent.
Thus the only one that is a polynomial is the second one, or x^4 - 2.