Problems 12–21. The purpose of these problems is to keep the material fresh in your mind so that you are better prepared for later sections, a final exam, or subsequent courses such as calculus.

Use the Intermediate Value Theorem to show that f (x) = −x⁴ + 2x³ − 5x + 1 has a zero in the interval [−2, −1]. Then, approximate the zero correct to two decimal places.