Visual representation of a data set or a mathematical equation , inequality , or function to show relationships or tendencies that these formulas can only suggest symbolically and abstractly.
Though histograms and pie charts are also graphs, the term usually applies to point plots on a coordinate system . For example, a graph of the relationship between real numbers and their squares matches each real number on a horizontal axis with its square on a vertical axis. The resulting set of points in this case is a parabola . A graph of an inequality is usually a shaded region on one side of a curve, whose shape depends not only on the equation or inequality but on the coordinate system chosen.