| Step | Hyp | Ref | Expression | 
						
							| 1 |  | ringneg.1 |  | 
						
							| 2 |  | ringneg.2 |  | 
						
							| 3 |  | ringneg.3 |  | 
						
							| 4 |  | ringneg.4 |  | 
						
							| 5 |  | ringneg.5 |  | 
						
							| 6 | 1 | rneqi |  | 
						
							| 7 | 3 6 | eqtri |  | 
						
							| 8 | 7 2 5 | rngo1cl |  | 
						
							| 9 | 1 3 4 | rngonegcl |  | 
						
							| 10 | 8 9 | mpdan |  | 
						
							| 11 | 8 10 | jca |  | 
						
							| 12 | 1 2 3 | rngodir |  | 
						
							| 13 | 12 | 3exp2 |  | 
						
							| 14 | 13 | imp42 |  | 
						
							| 15 | 14 | an32s |  | 
						
							| 16 | 11 15 | mpidan |  | 
						
							| 17 |  | eqid |  | 
						
							| 18 | 1 3 4 17 | rngoaddneg1 |  | 
						
							| 19 | 8 18 | mpdan |  | 
						
							| 20 | 19 | adantr |  | 
						
							| 21 | 20 | oveq1d |  | 
						
							| 22 | 17 3 1 2 | rngolz |  | 
						
							| 23 | 21 22 | eqtrd |  | 
						
							| 24 | 2 7 5 | rngolidm |  | 
						
							| 25 | 24 | oveq1d |  | 
						
							| 26 | 16 23 25 | 3eqtr3rd |  | 
						
							| 27 | 1 2 3 | rngocl |  | 
						
							| 28 | 27 | 3expa |  | 
						
							| 29 | 28 | an32s |  | 
						
							| 30 | 10 29 | mpidan |  | 
						
							| 31 | 1 | rngogrpo |  | 
						
							| 32 | 3 17 4 | grpoinvid1 |  | 
						
							| 33 | 31 32 | syl3an1 |  | 
						
							| 34 | 30 33 | mpd3an3 |  | 
						
							| 35 | 26 34 | mpbird |  |