A [u]linear function[/u] is a function of x, where x is not raised to any exponent except 1 or 0, [br](because [math]x^1=x[/math] and [math]x^0=1[/math]). [color=#0000ff][url=https://www.mathsisfun.com/algebra/exponent-laws.html]More on exponents here[/url] [code][/code][/color]