| Step | Hyp | Ref | Expression | 
						
							| 1 |  | zcn |  |-  ( x e. ZZ -> x e. CC ) | 
						
							| 2 |  | zaddcl |  |-  ( ( x e. ZZ /\ y e. ZZ ) -> ( x + y ) e. ZZ ) | 
						
							| 3 |  | znegcl |  |-  ( x e. ZZ -> -u x e. ZZ ) | 
						
							| 4 |  | 1z |  |-  1 e. ZZ | 
						
							| 5 | 1 2 3 4 | cnsubglem |  |-  ZZ e. ( SubGrp ` CCfld ) | 
						
							| 6 |  | eqid |  |-  ( .g ` CCfld ) = ( .g ` CCfld ) | 
						
							| 7 |  | df-zring |  |-  ZZring = ( CCfld |`s ZZ ) | 
						
							| 8 |  | eqid |  |-  ( .g ` ZZring ) = ( .g ` ZZring ) | 
						
							| 9 | 6 7 8 | subgmulg |  |-  ( ( ZZ e. ( SubGrp ` CCfld ) /\ A e. ZZ /\ B e. ZZ ) -> ( A ( .g ` CCfld ) B ) = ( A ( .g ` ZZring ) B ) ) | 
						
							| 10 | 5 9 | mp3an1 |  |-  ( ( A e. ZZ /\ B e. ZZ ) -> ( A ( .g ` CCfld ) B ) = ( A ( .g ` ZZring ) B ) ) | 
						
							| 11 |  | simpr |  |-  ( ( A e. ZZ /\ B e. ZZ ) -> B e. ZZ ) | 
						
							| 12 | 11 | zcnd |  |-  ( ( A e. ZZ /\ B e. ZZ ) -> B e. CC ) | 
						
							| 13 |  | cnfldmulg |  |-  ( ( A e. ZZ /\ B e. CC ) -> ( A ( .g ` CCfld ) B ) = ( A x. B ) ) | 
						
							| 14 | 12 13 | syldan |  |-  ( ( A e. ZZ /\ B e. ZZ ) -> ( A ( .g ` CCfld ) B ) = ( A x. B ) ) | 
						
							| 15 | 10 14 | eqtr3d |  |-  ( ( A e. ZZ /\ B e. ZZ ) -> ( A ( .g ` ZZring ) B ) = ( A x. B ) ) |