Chapter 2 - Limits - 2.4 Limits and Continuity - Exercises - Page 66: 10

All polynomials are continuous on the real line.

We are given the function $ f(x)=3x^3+8x^2-20x $. The function $ f(x)$ is a polynomial of degree 3. Theorem 2 states that all polynomials are continuous on the real line. Thus $$ f(x)=3x^3+8x^2-20x $$ is continuous.