How are linear equations used?
Linear equations are handy whenever one quantity changes directly as another one changes. For instance, the amount of gas you need to drive a certain distance, or how far something might travel at any particular speed. The equation can give you the answer without having to draw a graph. It can also tell you where multiple lines on the same graph would cross, without actually drawing the lines. Linear equations are an example of algebra influencing geometry. While traditional geometry meant you had to draw diagrams with a ruler and compass, using just the algebraic formulas means you can find the same answer by manipulating equations. Who invented linear equations? Linear equations are as old as algebra, although their use in graphing relationships (like where two lines cross) falls under coordinate graphing, which is an idea credited to Descartes, in the 17th century. The main ideas were expanded into more than two dimensions and multiple variables with the advent of linear algebra, wh
