| Step | Hyp | Ref | Expression | 
						
							| 1 |  | nvrinv.1 | ⊢ 𝑋  =  ( BaseSet ‘ 𝑈 ) | 
						
							| 2 |  | nvrinv.2 | ⊢ 𝐺  =  (  +𝑣  ‘ 𝑈 ) | 
						
							| 3 |  | nvrinv.4 | ⊢ 𝑆  =  (  ·𝑠OLD  ‘ 𝑈 ) | 
						
							| 4 |  | nvrinv.6 | ⊢ 𝑍  =  ( 0vec ‘ 𝑈 ) | 
						
							| 5 | 2 | nvgrp | ⊢ ( 𝑈  ∈  NrmCVec  →  𝐺  ∈  GrpOp ) | 
						
							| 6 | 1 2 | bafval | ⊢ 𝑋  =  ran  𝐺 | 
						
							| 7 |  | eqid | ⊢ ( GId ‘ 𝐺 )  =  ( GId ‘ 𝐺 ) | 
						
							| 8 |  | eqid | ⊢ ( inv ‘ 𝐺 )  =  ( inv ‘ 𝐺 ) | 
						
							| 9 | 6 7 8 | grpolinv | ⊢ ( ( 𝐺  ∈  GrpOp  ∧  𝐴  ∈  𝑋 )  →  ( ( ( inv ‘ 𝐺 ) ‘ 𝐴 ) 𝐺 𝐴 )  =  ( GId ‘ 𝐺 ) ) | 
						
							| 10 | 5 9 | sylan | ⊢ ( ( 𝑈  ∈  NrmCVec  ∧  𝐴  ∈  𝑋 )  →  ( ( ( inv ‘ 𝐺 ) ‘ 𝐴 ) 𝐺 𝐴 )  =  ( GId ‘ 𝐺 ) ) | 
						
							| 11 | 1 2 3 8 | nvinv | ⊢ ( ( 𝑈  ∈  NrmCVec  ∧  𝐴  ∈  𝑋 )  →  ( - 1 𝑆 𝐴 )  =  ( ( inv ‘ 𝐺 ) ‘ 𝐴 ) ) | 
						
							| 12 | 11 | oveq1d | ⊢ ( ( 𝑈  ∈  NrmCVec  ∧  𝐴  ∈  𝑋 )  →  ( ( - 1 𝑆 𝐴 ) 𝐺 𝐴 )  =  ( ( ( inv ‘ 𝐺 ) ‘ 𝐴 ) 𝐺 𝐴 ) ) | 
						
							| 13 | 2 4 | 0vfval | ⊢ ( 𝑈  ∈  NrmCVec  →  𝑍  =  ( GId ‘ 𝐺 ) ) | 
						
							| 14 | 13 | adantr | ⊢ ( ( 𝑈  ∈  NrmCVec  ∧  𝐴  ∈  𝑋 )  →  𝑍  =  ( GId ‘ 𝐺 ) ) | 
						
							| 15 | 10 12 14 | 3eqtr4d | ⊢ ( ( 𝑈  ∈  NrmCVec  ∧  𝐴  ∈  𝑋 )  →  ( ( - 1 𝑆 𝐴 ) 𝐺 𝐴 )  =  𝑍 ) |