| Step | Hyp | Ref | Expression | 
						
							| 1 |  | nfra1 |  | 
						
							| 2 |  | eqeq1 |  | 
						
							| 3 | 2 | rexbidv |  | 
						
							| 4 | 3 | 2rexbidv |  | 
						
							| 5 | 4 | cbvralvw |  | 
						
							| 6 |  | 6nn |  | 
						
							| 7 | 6 | nnzi |  | 
						
							| 8 | 7 | a1i |  | 
						
							| 9 |  | evenz |  | 
						
							| 10 |  | 2z |  | 
						
							| 11 | 10 | a1i |  | 
						
							| 12 | 9 11 | zaddcld |  | 
						
							| 13 | 12 | adantr |  | 
						
							| 14 |  | 4cn |  | 
						
							| 15 |  | 2cn |  | 
						
							| 16 |  | 4p2e6 |  | 
						
							| 17 | 16 | eqcomi |  | 
						
							| 18 | 14 15 17 | mvrraddi |  | 
						
							| 19 |  | 2p2e4 |  | 
						
							| 20 |  | 2evenALTV |  | 
						
							| 21 |  | evenltle |  | 
						
							| 22 | 20 21 | mp3an2 |  | 
						
							| 23 | 19 22 | eqbrtrrid |  | 
						
							| 24 | 18 23 | eqbrtrid |  | 
						
							| 25 |  | 6re |  | 
						
							| 26 | 25 | a1i |  | 
						
							| 27 |  | 2re |  | 
						
							| 28 | 27 | a1i |  | 
						
							| 29 | 9 | zred |  | 
						
							| 30 | 26 28 29 | 3jca |  | 
						
							| 31 | 30 | adantr |  | 
						
							| 32 |  | lesubadd |  | 
						
							| 33 | 31 32 | syl |  | 
						
							| 34 | 24 33 | mpbid |  | 
						
							| 35 |  | eluz2 |  | 
						
							| 36 | 8 13 34 35 | syl3anbrc |  | 
						
							| 37 |  | eqeq1 |  | 
						
							| 38 | 37 | rexbidv |  | 
						
							| 39 | 38 | 2rexbidv |  | 
						
							| 40 | 39 | rspcv |  | 
						
							| 41 | 36 40 | syl |  | 
						
							| 42 | 5 41 | biimtrid |  | 
						
							| 43 |  | nfv |  | 
						
							| 44 |  | nfre1 |  | 
						
							| 45 |  | nfv |  | 
						
							| 46 |  | nfcv |  | 
						
							| 47 |  | nfre1 |  | 
						
							| 48 | 46 47 | nfrexw |  | 
						
							| 49 |  | simplrl |  | 
						
							| 50 |  | simplrr |  | 
						
							| 51 |  | simpr |  | 
						
							| 52 | 49 50 51 | 3jca |  | 
						
							| 53 | 52 | adantr |  | 
						
							| 54 |  | simp-4l |  | 
						
							| 55 |  | simpr |  | 
						
							| 56 |  | mogoldbblem |  | 
						
							| 57 |  | oveq1 |  | 
						
							| 58 | 57 | eqeq2d |  | 
						
							| 59 |  | oveq2 |  | 
						
							| 60 | 59 | eqeq2d |  | 
						
							| 61 | 58 60 | cbvrex2vw |  | 
						
							| 62 | 56 61 | sylibr |  | 
						
							| 63 | 53 54 55 62 | syl3anc |  | 
						
							| 64 | 63 | rexlimdva2 |  | 
						
							| 65 | 64 | expr |  | 
						
							| 66 | 45 48 65 | rexlimd |  | 
						
							| 67 | 66 | ex |  | 
						
							| 68 | 43 44 67 | rexlimd |  | 
						
							| 69 | 42 68 | syldc |  | 
						
							| 70 | 69 | expd |  | 
						
							| 71 | 1 70 | ralrimi |  |