Is this a polynomial?

15x – 12 + 4x

I'm pretty sure it is a polynomial, am I right?

4 answers

No.

A polynomial needs an exponent.

http://www.mathsisfun.com/algebra/polynomials.html
Okay, so if it was 15x^3 - 12 + 4x^3, then it would be a polynomial?
Yes. Only 1 exponent is needed for it to be a polynomial.
Wait, I just realized that 15x – 12 + 4x is a polynomial because the x is automatically x^1, so yeah. Also in the link you gave me it says that x - 2 and 3x are both polynomials. Therefore, it technically would be a polynomial.