Solve y′=ex−yy' = e^{x-y}y′=ex−y.
ey=ex+Ce^y = e^x + Cey=ex+C
ey=e−x+Ce^y = e^{-x} + Cey=e−x+C
e−y=ex+Ce^{-y} = e^x + Ce−y=ex+C
y=ln(ex+C)y = \ln(e^x + C)y=ln(ex+C)