theorem :: DIFF_3:5

for n being Element of NAT
for h, r, x being Real
for f1, f2 being Function of REAL,REAL holds ((fdif ((f1 + (r (#) f2)),h)) . (n + 1)) . x = (((fdif (f1,h)) . (n + 1)) . x) + (r * (((fdif (f2,h)) . (n + 1)) . x))