f'(x)=e^(2x-1) *(2x-1)'=2e^(2x-1)
f（x）=e^（2x-1)f '（x）=[e^（2x-1)](2x-1)'=2e^（2x-1)
[e^(kx+c)]'=ke^(kx+c)[e^(kx+c)]''=k^2e^(kx+c)[e^(kx+c)]'''=k^3e^(kx+c):
