Answer:

1. The critical numbers are the values of x for which an inequality equals 0 or is undefined. They break the number line into segments, called intervals. Pretend the inequality symbol is an equal sign and solve the corresponding quadratic equation. Those solutions are called the critical numbers of the inequality.

2.So why are quadratic functions important? Quadratic functions hold a unique position in the school curriculum. They are functions whose values can be easily calculated from input values, so they are a slight advance on linear functions and provide a significant move away from attachment to straight lines.