# First let's setup our sympy powered IPython Notebook environment...
from IPython.display import display, Latex
from sympy.interactive import printing
printing.init_printing()
import sympy
from sympy import *
x, k = sympy.symbols('x k')
f = sympy.Function('f')
dfdx_expr = x*sympy.exp(-k*x)
sol = dsolve(f(x).diff(x)-dfdx_expr,f(x))
sol
refine(sol, Q.is_true(Eq(k**3, 0)))
refine(sol, Q.is_true(Eq(k**3, 1)))