# Linear equations

A linear equation is an equation for a straight line. When plotted on a graph, a linear equation results in a straight line.

Below are some examples of linear equations:

Examples

y = ½x - 3

x = -2

y = 4

In contrast, the following is not a linear equation (it is quadratic):

y = x^{2} - 6

There is a special linear equation called the identity function. Inputting any x-value will return the same value of y. Its equation is y = x:

Linear equations have a constant slope. Linear equations are most commonly represented in slope-intercept, point-slope, and standard form.

See also slope, point slope form, standard form.