meaning "start with some value of x, calculate the right hand side, and use the result as a new value of x". It may be objected that this is a misuse of the = symbol, and that the above is...meaning "start with some value of x, calculate the right hand side, and use the result as a new value of x". It may be objected that this is a misuse of the = symbol, and that the above is not really an "Equation", since x cannot equal x minus something.