Linear Relationships

Almost every real cost you meet has a "starting amount" and a "rate". A taxi charges a flag-fall plus a rate per kilometre; a phone bill is a fixed rental plus a charge per minute; a salary is a basic wage plus a commission per sale. Each of these is a linear relationship — the very idea you master here. And when a quantity depends on a squared amount — the area of a square garden, the path of a cricket ball flying to the boundary — the picture bends into a parabola. In this lesson you learn to read both from their equations and their graphs, which is the foundation for coordinate geometry and functions right through your O/L.