Question 157286
Not to be a wise guy, but non-linear functions are those which are not linear. 
In other words, when you graph it, it's not a straight line.
Also, it cannot be represented with the formula,
{{{y=mx+b}}}
Also, linear functions give a constant {{{DELTA*y}}} for a constant {{{DELTA*x}}} because the slope is constant.
That is not the case for nonlinear functions.