Metamath Proof Explorer


Theorem sn-addid0

Description: A number that sums to itself is zero. Compare addid0 , readdid1addid2d . (Contributed by SN, 5-May-2024)

Ref Expression
Hypotheses sn-addid0.a
|- ( ph -> A e. CC )
sn-addid0.1
|- ( ph -> ( A + A ) = A )
Assertion sn-addid0
|- ( ph -> A = 0 )

Proof

Step Hyp Ref Expression
1 sn-addid0.a
 |-  ( ph -> A e. CC )
2 sn-addid0.1
 |-  ( ph -> ( A + A ) = A )
3 sn-addid1
 |-  ( A e. CC -> ( A + 0 ) = A )
4 1 3 syl
 |-  ( ph -> ( A + 0 ) = A )
5 2 4 eqtr4d
 |-  ( ph -> ( A + A ) = ( A + 0 ) )
6 0cnd
 |-  ( ph -> 0 e. CC )
7 1 1 6 sn-addcand
 |-  ( ph -> ( ( A + A ) = ( A + 0 ) <-> A = 0 ) )
8 5 7 mpbid
 |-  ( ph -> A = 0 )