| Step | Hyp | Ref | Expression | 
						
							| 1 |  | neg1z |  |-  -u 1 e. ZZ | 
						
							| 2 |  | rmxadd |  |-  ( ( A e. ( ZZ>= ` 2 ) /\ N e. ZZ /\ -u 1 e. ZZ ) -> ( A rmX ( N + -u 1 ) ) = ( ( ( A rmX N ) x. ( A rmX -u 1 ) ) + ( ( ( A ^ 2 ) - 1 ) x. ( ( A rmY N ) x. ( A rmY -u 1 ) ) ) ) ) | 
						
							| 3 | 1 2 | mp3an3 |  |-  ( ( A e. ( ZZ>= ` 2 ) /\ N e. ZZ ) -> ( A rmX ( N + -u 1 ) ) = ( ( ( A rmX N ) x. ( A rmX -u 1 ) ) + ( ( ( A ^ 2 ) - 1 ) x. ( ( A rmY N ) x. ( A rmY -u 1 ) ) ) ) ) | 
						
							| 4 |  | 1z |  |-  1 e. ZZ | 
						
							| 5 |  | rmxneg |  |-  ( ( A e. ( ZZ>= ` 2 ) /\ 1 e. ZZ ) -> ( A rmX -u 1 ) = ( A rmX 1 ) ) | 
						
							| 6 | 4 5 | mpan2 |  |-  ( A e. ( ZZ>= ` 2 ) -> ( A rmX -u 1 ) = ( A rmX 1 ) ) | 
						
							| 7 |  | rmx1 |  |-  ( A e. ( ZZ>= ` 2 ) -> ( A rmX 1 ) = A ) | 
						
							| 8 | 6 7 | eqtrd |  |-  ( A e. ( ZZ>= ` 2 ) -> ( A rmX -u 1 ) = A ) | 
						
							| 9 | 8 | adantr |  |-  ( ( A e. ( ZZ>= ` 2 ) /\ N e. ZZ ) -> ( A rmX -u 1 ) = A ) | 
						
							| 10 | 9 | oveq2d |  |-  ( ( A e. ( ZZ>= ` 2 ) /\ N e. ZZ ) -> ( ( A rmX N ) x. ( A rmX -u 1 ) ) = ( ( A rmX N ) x. A ) ) | 
						
							| 11 |  | frmx |  |-  rmX : ( ( ZZ>= ` 2 ) X. ZZ ) --> NN0 | 
						
							| 12 | 11 | fovcl |  |-  ( ( A e. ( ZZ>= ` 2 ) /\ N e. ZZ ) -> ( A rmX N ) e. NN0 ) | 
						
							| 13 | 12 | nn0cnd |  |-  ( ( A e. ( ZZ>= ` 2 ) /\ N e. ZZ ) -> ( A rmX N ) e. CC ) | 
						
							| 14 |  | eluzelcn |  |-  ( A e. ( ZZ>= ` 2 ) -> A e. CC ) | 
						
							| 15 | 14 | adantr |  |-  ( ( A e. ( ZZ>= ` 2 ) /\ N e. ZZ ) -> A e. CC ) | 
						
							| 16 | 13 15 | mulcomd |  |-  ( ( A e. ( ZZ>= ` 2 ) /\ N e. ZZ ) -> ( ( A rmX N ) x. A ) = ( A x. ( A rmX N ) ) ) | 
						
							| 17 | 10 16 | eqtrd |  |-  ( ( A e. ( ZZ>= ` 2 ) /\ N e. ZZ ) -> ( ( A rmX N ) x. ( A rmX -u 1 ) ) = ( A x. ( A rmX N ) ) ) | 
						
							| 18 |  | rmyneg |  |-  ( ( A e. ( ZZ>= ` 2 ) /\ 1 e. ZZ ) -> ( A rmY -u 1 ) = -u ( A rmY 1 ) ) | 
						
							| 19 | 4 18 | mpan2 |  |-  ( A e. ( ZZ>= ` 2 ) -> ( A rmY -u 1 ) = -u ( A rmY 1 ) ) | 
						
							| 20 |  | rmy1 |  |-  ( A e. ( ZZ>= ` 2 ) -> ( A rmY 1 ) = 1 ) | 
						
							| 21 | 20 | negeqd |  |-  ( A e. ( ZZ>= ` 2 ) -> -u ( A rmY 1 ) = -u 1 ) | 
						
							| 22 | 19 21 | eqtrd |  |-  ( A e. ( ZZ>= ` 2 ) -> ( A rmY -u 1 ) = -u 1 ) | 
						
							| 23 | 22 | oveq2d |  |-  ( A e. ( ZZ>= ` 2 ) -> ( ( A rmY N ) x. ( A rmY -u 1 ) ) = ( ( A rmY N ) x. -u 1 ) ) | 
						
							| 24 | 23 | adantr |  |-  ( ( A e. ( ZZ>= ` 2 ) /\ N e. ZZ ) -> ( ( A rmY N ) x. ( A rmY -u 1 ) ) = ( ( A rmY N ) x. -u 1 ) ) | 
						
							| 25 |  | frmy |  |-  rmY : ( ( ZZ>= ` 2 ) X. ZZ ) --> ZZ | 
						
							| 26 | 25 | fovcl |  |-  ( ( A e. ( ZZ>= ` 2 ) /\ N e. ZZ ) -> ( A rmY N ) e. ZZ ) | 
						
							| 27 | 26 | zcnd |  |-  ( ( A e. ( ZZ>= ` 2 ) /\ N e. ZZ ) -> ( A rmY N ) e. CC ) | 
						
							| 28 |  | ax-1cn |  |-  1 e. CC | 
						
							| 29 |  | mulneg2 |  |-  ( ( ( A rmY N ) e. CC /\ 1 e. CC ) -> ( ( A rmY N ) x. -u 1 ) = -u ( ( A rmY N ) x. 1 ) ) | 
						
							| 30 | 27 28 29 | sylancl |  |-  ( ( A e. ( ZZ>= ` 2 ) /\ N e. ZZ ) -> ( ( A rmY N ) x. -u 1 ) = -u ( ( A rmY N ) x. 1 ) ) | 
						
							| 31 | 27 | mulridd |  |-  ( ( A e. ( ZZ>= ` 2 ) /\ N e. ZZ ) -> ( ( A rmY N ) x. 1 ) = ( A rmY N ) ) | 
						
							| 32 | 31 | negeqd |  |-  ( ( A e. ( ZZ>= ` 2 ) /\ N e. ZZ ) -> -u ( ( A rmY N ) x. 1 ) = -u ( A rmY N ) ) | 
						
							| 33 | 30 32 | eqtrd |  |-  ( ( A e. ( ZZ>= ` 2 ) /\ N e. ZZ ) -> ( ( A rmY N ) x. -u 1 ) = -u ( A rmY N ) ) | 
						
							| 34 | 24 33 | eqtrd |  |-  ( ( A e. ( ZZ>= ` 2 ) /\ N e. ZZ ) -> ( ( A rmY N ) x. ( A rmY -u 1 ) ) = -u ( A rmY N ) ) | 
						
							| 35 | 34 | oveq2d |  |-  ( ( A e. ( ZZ>= ` 2 ) /\ N e. ZZ ) -> ( ( ( A ^ 2 ) - 1 ) x. ( ( A rmY N ) x. ( A rmY -u 1 ) ) ) = ( ( ( A ^ 2 ) - 1 ) x. -u ( A rmY N ) ) ) | 
						
							| 36 |  | rmspecnonsq |  |-  ( A e. ( ZZ>= ` 2 ) -> ( ( A ^ 2 ) - 1 ) e. ( NN \ []NN ) ) | 
						
							| 37 | 36 | eldifad |  |-  ( A e. ( ZZ>= ` 2 ) -> ( ( A ^ 2 ) - 1 ) e. NN ) | 
						
							| 38 | 37 | nncnd |  |-  ( A e. ( ZZ>= ` 2 ) -> ( ( A ^ 2 ) - 1 ) e. CC ) | 
						
							| 39 | 38 | adantr |  |-  ( ( A e. ( ZZ>= ` 2 ) /\ N e. ZZ ) -> ( ( A ^ 2 ) - 1 ) e. CC ) | 
						
							| 40 | 39 27 | mulneg2d |  |-  ( ( A e. ( ZZ>= ` 2 ) /\ N e. ZZ ) -> ( ( ( A ^ 2 ) - 1 ) x. -u ( A rmY N ) ) = -u ( ( ( A ^ 2 ) - 1 ) x. ( A rmY N ) ) ) | 
						
							| 41 | 35 40 | eqtrd |  |-  ( ( A e. ( ZZ>= ` 2 ) /\ N e. ZZ ) -> ( ( ( A ^ 2 ) - 1 ) x. ( ( A rmY N ) x. ( A rmY -u 1 ) ) ) = -u ( ( ( A ^ 2 ) - 1 ) x. ( A rmY N ) ) ) | 
						
							| 42 | 17 41 | oveq12d |  |-  ( ( A e. ( ZZ>= ` 2 ) /\ N e. ZZ ) -> ( ( ( A rmX N ) x. ( A rmX -u 1 ) ) + ( ( ( A ^ 2 ) - 1 ) x. ( ( A rmY N ) x. ( A rmY -u 1 ) ) ) ) = ( ( A x. ( A rmX N ) ) + -u ( ( ( A ^ 2 ) - 1 ) x. ( A rmY N ) ) ) ) | 
						
							| 43 | 3 42 | eqtrd |  |-  ( ( A e. ( ZZ>= ` 2 ) /\ N e. ZZ ) -> ( A rmX ( N + -u 1 ) ) = ( ( A x. ( A rmX N ) ) + -u ( ( ( A ^ 2 ) - 1 ) x. ( A rmY N ) ) ) ) | 
						
							| 44 |  | zcn |  |-  ( N e. ZZ -> N e. CC ) | 
						
							| 45 | 44 | adantl |  |-  ( ( A e. ( ZZ>= ` 2 ) /\ N e. ZZ ) -> N e. CC ) | 
						
							| 46 |  | negsub |  |-  ( ( N e. CC /\ 1 e. CC ) -> ( N + -u 1 ) = ( N - 1 ) ) | 
						
							| 47 | 45 28 46 | sylancl |  |-  ( ( A e. ( ZZ>= ` 2 ) /\ N e. ZZ ) -> ( N + -u 1 ) = ( N - 1 ) ) | 
						
							| 48 | 47 | oveq2d |  |-  ( ( A e. ( ZZ>= ` 2 ) /\ N e. ZZ ) -> ( A rmX ( N + -u 1 ) ) = ( A rmX ( N - 1 ) ) ) | 
						
							| 49 | 15 13 | mulcld |  |-  ( ( A e. ( ZZ>= ` 2 ) /\ N e. ZZ ) -> ( A x. ( A rmX N ) ) e. CC ) | 
						
							| 50 | 39 27 | mulcld |  |-  ( ( A e. ( ZZ>= ` 2 ) /\ N e. ZZ ) -> ( ( ( A ^ 2 ) - 1 ) x. ( A rmY N ) ) e. CC ) | 
						
							| 51 | 49 50 | negsubd |  |-  ( ( A e. ( ZZ>= ` 2 ) /\ N e. ZZ ) -> ( ( A x. ( A rmX N ) ) + -u ( ( ( A ^ 2 ) - 1 ) x. ( A rmY N ) ) ) = ( ( A x. ( A rmX N ) ) - ( ( ( A ^ 2 ) - 1 ) x. ( A rmY N ) ) ) ) | 
						
							| 52 | 43 48 51 | 3eqtr3d |  |-  ( ( A e. ( ZZ>= ` 2 ) /\ N e. ZZ ) -> ( A rmX ( N - 1 ) ) = ( ( A x. ( A rmX N ) ) - ( ( ( A ^ 2 ) - 1 ) x. ( A rmY N ) ) ) ) |