Answer:
the answer is x³-1.
Explanation:
A cubic polynomial is a polynomial of degree 3, which means that the highest exponent of the variable is 3. Of the four options given, only the expression x³-1 has a variable with exponent 3. Therefore, the expression x³-1 is a cubic polynomial.
The other three options are not cubic polynomials:
3x² -1 is a quadratic polynomial, since the highest exponent of the variable is 2.
x²-x+3 is a quadratic polynomial, since the highest exponent of the variable is 2.
3x²-x+3 is a quadratic polynomial, since the highest exponent of the variable is 2.