intros a b H'; inversion H'.
cut (~ zeroP (A:=A) A0 eqA (n:=n) (invTerm (A:=A) invA (n:=n) b));
[ intros nZib | auto ].
apply divTerm_def with (nZb := nZib); auto.
apply
(eqTerm_trans _ _ _ _ _ _ _ _ _ cs n)
with
(y := multTerm (A:=A) multA (n:=n)
(invTerm (A:=A) invA (n:=n) (divTerm a nZb))
(invTerm (A:=A) invA (n:=n) b)); auto.
apply
(eqTerm_trans _ _ _ _ _ _ _ _ _ cs n)
with
(y := invTerm (A:=A) invA (n:=n)
(multTerm (A:=A) multA (n:=n) (divTerm a nZb)
(invTerm (A:=A) invA (n:=n) b))); auto.
apply
(eqTerm_trans _ _ _ _ _ _ _ _ _ cs n)
with
(y := invTerm (A:=A) invA (n:=n)
(invTerm (A:=A) invA (n:=n)
(multTerm (A:=A) multA (n:=n) (divTerm a nZb) b)));
auto.
apply
(eqTerm_trans _ _ _ _ _ _ _ _ _ cs n)
with (y := multTerm (A:=A) multA (n:=n) (divTerm a nZb) b);
auto.
apply eqTerm_invTerm_comp with (1 := cs); auto.
apply (eqTerm_sym _ _ _ _ _ _ _ _ _ cs n);
apply mult_invTerm_com_r with (1 := cs); auto.
apply (eqTerm_sym _ _ _ _ _ _ _ _ _ cs n);
apply mult_invTerm_com with (1 := cs); auto.
apply eqTerm_multTerm_comp with (1 := cs); auto.
apply (eqTerm_sym _ _ _ _ _ _ _ _ _ cs n); apply divTerm_invTerm_r; auto.
Qed.
Hint Resolve divTerm_nZ.
Hint Resolve divP_invTerm_r.

Theorem divTerm_multTerml :
forall a b : Term A n,
~ zeroP (A:=A) A0 eqA (n:=n) a ->
~ zeroP (A:=A) A0 eqA (n:=n) b -> divP (multTerm (A:=A) multA (n:=n) a b) a.