# Which of these is an example of a linear equation?

##
#6x+9y=5#

#x^2-y^3=1#

##### 1 Answer

Linear equation:

Non-linear equation:

#### Explanation:

A **linear equation** is one where the only degree of any variable in the equation is 1 (no squares, cubes, square roots, etc.). A graph of any such equation will have no "curvature" to it at all. One variable is expressible as a sum of multiples of the other variables (plus a possible constant), resulting in a flat line/plane (hence "linear").

A sample graph of the linear equation

graph{6x+9y=5 [-10, 10, -5, 5]}

A **non-linear equation** is any equation that has *at least one variable with an exponent other than 1* in it. A graph of any non-linear equation will have curvature (i.e. it will not be straight everywhere).

A sample graph of the non-linear equation

graph{x^2-y^3=1 [-10, 10, -5, 5]}