## Calculus (3rd Edition)

All the polynomials of the form: $$f(x)=a_0+a_1x+a_2x^2.$$
Any polynomial $f(x)$ of degree $2$ is given by $$f(x)=a_0+a_1x+a_2x^2.$$ Now, we have $$f'(x)=a_1+2a_2x, \quad f''(x)=2a_2$$ and hence $f'''(x)=0$ for all $x$.