OK here is my problem:

And these are my steps

*C1, C2, C3 = Csub1, Csub2, Csub3

y = C1e^0x + C2e^2x + C3e^-x

solution: y = C1 + C2e^2x + C3e^-x

but when checking the problem on Wolfram Alpha, the solution is:

y = C1 + (1/2)C2e^2x + C3(-e^-x)

Is there a step I'm missing?