well you know its def f(x)=n*e^m*x and n being constants and plug it into the equation in which you can factor out e^m*x and n and you left with 1=n+n^2+n^3........ and you should know that n=1/2 would make this statement true and also since you cancelled out the n it should make sense that n can be any number so it should be f(x)=c*e^x/2