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:
y = ½x - 3
x = -2
y = 4
In contrast, the following is not a linear equation (it is quadratic):
y = x2 - 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.