15/01/21 22:08:31.55 OPHJ2hAi.net
>>840
Require Import Arith.
Theorem t: forall n:nat, 2*n = n+n.
intros.
replace (n+n) with (1*n + 1*n).
replace 2 with (1+1).
apply mult_plus_distr_r.
auto.
replace (1*n) with n.
auto.
symmetry.
apply mult_1_l.
Qed.
15/01/21 22:08:31.55 OPHJ2hAi.net
>>840
Require Import Arith.
Theorem t: forall n:nat, 2*n = n+n.
intros.
replace (n+n) with (1*n + 1*n).
replace 2 with (1+1).
apply mult_plus_distr_r.
auto.
replace (1*n) with n.
auto.
symmetry.
apply mult_1_l.
Qed.