An equation of the form \(y = mx + c\) where \(m\) and \(c\) are numbers, gives a straight line when values of \(x\) and corresponding values of \(y\) are plotted on a grid. A straight line is a ...

Plotting a graph takes time. Often mathematicians just want to know the key features. These are: shape, location and some key points (such as where the graph crosses the axes or turning points).