An equation that forms a straight line on a graph.
More precisely, a linear equation is one that is dependent only on constants and a variable raised to the first power. For example, y=6x+2 is linear because it has no squares, cubes, square roots, sines, etc. Linear equations can always be manipulated to take this form:
ax+b=0
You won't always see linear equations written exactly like that, but keep in mind that we can manipulate equations to put them in a particular form if necessary.
Linear equations are often written with more than one variable, typically x and y. Such equations will have many possible combinations of x and y that work. When those points (known as coordinate pairs) are plotted on an x-y axis, they will form a straight line. Let's take a look at this graphically below. The two equations drawn are linear. Note that one is in the form y=3 (it is dependent on just a constant, 3), and the other equation is y=0.75x−0.5 (a linear term and a constant).
