#
# xpdf ../../EBook/Elementary_Differential_Equations_10th_Edition.pdf 261 &
#
import sympy
from sympy import *
t, A, B = symbols('t A B')
y = A * t**4 + B * t**3
pt1 = diff(y, t, 6)
pt2 = diff(y, t, 3)
residual = pt1 + pt2 - t
print(simplify(residual))