What are rational numbers used?
Due to decimals of many fractions having many numbers after the decimal point, most numbers that need to be accurate stay in the form of the fraction.
What is the point and application of a derivative?
In calculus and applied mathematics, a derivative of any equation that has a variable (x or higher power) will result in the equation of rate of change.
What is the purpose of the quadratic formula?
When 3 variables are present (x^2, x, and c), this constitutes a quadratic equation. To solve this equation, one must use the quadratic formula to obtain the variable solution.