Enter a trial function f(x) that can depend on up to two parameters a and b.[br][br]The goal is to find a function such that the sum of the function and its derivative vanishes for all x.[br][br]If both x and f(x) are quantities rather than numbers [[b][size=85]see "[i]Semantic Aspects of Quantity[/i]" on the [i]mathMINDhabits[/i] website[/size][/b]] explain how and why f(x) and f'(x) can be added.