Metamath Proof Explorer

Theorem subidd

Description: Subtraction of a number from itself. (Contributed by Mario Carneiro, 27-May-2016)

Ref Expression
Hypothesis negidd.1 
|- ( ph -> A e. CC )
Assertion subidd 
|- ( ph -> ( A - A ) = 0 )

Proof

Step Hyp Ref Expression
1 negidd.1 
 |-  ( ph -> A e. CC )
2 subid 
 |-  ( A e. CC -> ( A - A ) = 0 )
3 1 2 syl 
 |-  ( ph -> ( A - A ) = 0 )