Equations with exponents greater than one are non-linear. An example of a non-linear equation of two variables is

axy + b = 0, where a and b are constants and a ≠ 0.

In our case we have:

y = 8/(x - 6) multiply both sides by (x - 6)

y(x - 6) = 8

xy - 6y = 8

The above equation has a variables, x and y, and is non-linear because the sum of the exponents of the variables in the first term, xy, is 2 (greater than 1).