If for example, I have. Y1=Cos(2Ln(x)) and Y2=Sin(2Ln(x)) and I have to reach the general solution. I know how to get to the general solution is the cauchy equation: y'' X^n + y' x + 4 y = 0 According to the answer, n=2 => y'' X^2 + y' x + 4 y = 0 How am I to know that that it is X^2 ? Or is it always X^2 in a Euler Cauchy equation? Thanks in advance.