let S1, S2 be sequence of X; ( ( for n being Nat holds S1 . n = (S . n) * a ) & ( for n being Nat holds S2 . n = (S . n) * a ) implies S1 = S2 )
assume that
A5:
for n being Nat holds S1 . n = (S . n) * a
and
A6:
for n being Nat holds S2 . n = (S . n) * a
; S1 = S2
for n being Element of NAT holds S1 . n = S2 . n
hence
S1 = S2
by FUNCT_2:63; verum