Final answer:
The question seems to contain a typo as it asks to use the bisection method for a cubic function but provides reference information for solving a quadratic equation. The bisection method is a numerical approach for root-finding, which is usually not needed for quadratic equations that can be solved directly using the quadratic formula.
Step-by-step explanation:
The student's question deals with finding the roots of a cubic function using the bisection method. However, the provided reference information focuses on solving quadratic equations using the quadratic formula, ax²+bx+c = 0. It is not directly applicable to cubic functions.
To solve a cubic equation like f(x) = −12 − 21x + 18x² − 2.75x³, we would typically need either a numerical method like the bisection method or a specific cubic formula. Since the bisection method is requested, we should identify two points between which the function changes sign and then iteratively bisect this interval to narrow down the root.
A quadratic equation, such as x² + 0.0211x − 0.0211 = 0, can be solved using the quadratic formula x = −b ± √(b² − 4ac) / (2a). The reference to the bisection method may be a typo, as this numerical method is not generally used for quadratic equations, which can be solved analytically.