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Description: Lemma for zmulcom . (Contributed by SN, 25-Jan-2025)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | zmulcomlem | |- ( ( ( A e. RR /\ ( 0 -R A ) e. NN ) /\ B e. NN0 ) -> ( A x. B ) = ( B x. A ) ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | elnn0 | |- ( B e. NN0 <-> ( B e. NN \/ B = 0 ) ) |
|
| 2 | renegneg | |- ( A e. RR -> ( 0 -R ( 0 -R A ) ) = A ) |
|
| 3 | 2 | oveq1d | |- ( A e. RR -> ( ( 0 -R ( 0 -R A ) ) x. B ) = ( A x. B ) ) |
| 4 | 3 | ad2antrr | |- ( ( ( A e. RR /\ ( 0 -R A ) e. NN ) /\ B e. NN ) -> ( ( 0 -R ( 0 -R A ) ) x. B ) = ( A x. B ) ) |
| 5 | rernegcl | |- ( A e. RR -> ( 0 -R A ) e. RR ) |
|
| 6 | 5 | ad2antrr | |- ( ( ( A e. RR /\ ( 0 -R A ) e. NN ) /\ B e. NN ) -> ( 0 -R A ) e. RR ) |
| 7 | simpr | |- ( ( ( A e. RR /\ ( 0 -R A ) e. NN ) /\ B e. NN ) -> B e. NN ) |
|
| 8 | 6 7 | renegmulnnass | |- ( ( ( A e. RR /\ ( 0 -R A ) e. NN ) /\ B e. NN ) -> ( ( 0 -R ( 0 -R A ) ) x. B ) = ( 0 -R ( ( 0 -R A ) x. B ) ) ) |
| 9 | nnmulcom | |- ( ( ( 0 -R A ) e. NN /\ B e. NN ) -> ( ( 0 -R A ) x. B ) = ( B x. ( 0 -R A ) ) ) |
|
| 10 | 9 | adantll | |- ( ( ( A e. RR /\ ( 0 -R A ) e. NN ) /\ B e. NN ) -> ( ( 0 -R A ) x. B ) = ( B x. ( 0 -R A ) ) ) |
| 11 | 10 | oveq2d | |- ( ( ( A e. RR /\ ( 0 -R A ) e. NN ) /\ B e. NN ) -> ( 0 -R ( ( 0 -R A ) x. B ) ) = ( 0 -R ( B x. ( 0 -R A ) ) ) ) |
| 12 | nnre | |- ( B e. NN -> B e. RR ) |
|
| 13 | 12 | adantl | |- ( ( ( A e. RR /\ ( 0 -R A ) e. NN ) /\ B e. NN ) -> B e. RR ) |
| 14 | 0red | |- ( ( ( A e. RR /\ ( 0 -R A ) e. NN ) /\ B e. NN ) -> 0 e. RR ) |
|
| 15 | resubdi | |- ( ( B e. RR /\ 0 e. RR /\ ( 0 -R A ) e. RR ) -> ( B x. ( 0 -R ( 0 -R A ) ) ) = ( ( B x. 0 ) -R ( B x. ( 0 -R A ) ) ) ) |
|
| 16 | 13 14 6 15 | syl3anc | |- ( ( ( A e. RR /\ ( 0 -R A ) e. NN ) /\ B e. NN ) -> ( B x. ( 0 -R ( 0 -R A ) ) ) = ( ( B x. 0 ) -R ( B x. ( 0 -R A ) ) ) ) |
| 17 | remul01 | |- ( B e. RR -> ( B x. 0 ) = 0 ) |
|
| 18 | 12 17 | syl | |- ( B e. NN -> ( B x. 0 ) = 0 ) |
| 19 | 18 | adantl | |- ( ( ( A e. RR /\ ( 0 -R A ) e. NN ) /\ B e. NN ) -> ( B x. 0 ) = 0 ) |
| 20 | 19 | oveq1d | |- ( ( ( A e. RR /\ ( 0 -R A ) e. NN ) /\ B e. NN ) -> ( ( B x. 0 ) -R ( B x. ( 0 -R A ) ) ) = ( 0 -R ( B x. ( 0 -R A ) ) ) ) |
| 21 | 16 20 | eqtrd | |- ( ( ( A e. RR /\ ( 0 -R A ) e. NN ) /\ B e. NN ) -> ( B x. ( 0 -R ( 0 -R A ) ) ) = ( 0 -R ( B x. ( 0 -R A ) ) ) ) |
| 22 | 2 | ad2antrr | |- ( ( ( A e. RR /\ ( 0 -R A ) e. NN ) /\ B e. NN ) -> ( 0 -R ( 0 -R A ) ) = A ) |
| 23 | 22 | oveq2d | |- ( ( ( A e. RR /\ ( 0 -R A ) e. NN ) /\ B e. NN ) -> ( B x. ( 0 -R ( 0 -R A ) ) ) = ( B x. A ) ) |
| 24 | 11 21 23 | 3eqtr2d | |- ( ( ( A e. RR /\ ( 0 -R A ) e. NN ) /\ B e. NN ) -> ( 0 -R ( ( 0 -R A ) x. B ) ) = ( B x. A ) ) |
| 25 | 8 4 24 | 3eqtr3d | |- ( ( ( A e. RR /\ ( 0 -R A ) e. NN ) /\ B e. NN ) -> ( A x. B ) = ( B x. A ) ) |
| 26 | 4 4 25 | 3eqtr3d | |- ( ( ( A e. RR /\ ( 0 -R A ) e. NN ) /\ B e. NN ) -> ( A x. B ) = ( B x. A ) ) |
| 27 | remul01 | |- ( A e. RR -> ( A x. 0 ) = 0 ) |
|
| 28 | remul02 | |- ( A e. RR -> ( 0 x. A ) = 0 ) |
|
| 29 | 27 28 | eqtr4d | |- ( A e. RR -> ( A x. 0 ) = ( 0 x. A ) ) |
| 30 | 29 | adantr | |- ( ( A e. RR /\ ( 0 -R A ) e. NN ) -> ( A x. 0 ) = ( 0 x. A ) ) |
| 31 | oveq2 | |- ( B = 0 -> ( A x. B ) = ( A x. 0 ) ) |
|
| 32 | oveq1 | |- ( B = 0 -> ( B x. A ) = ( 0 x. A ) ) |
|
| 33 | 31 32 | eqeq12d | |- ( B = 0 -> ( ( A x. B ) = ( B x. A ) <-> ( A x. 0 ) = ( 0 x. A ) ) ) |
| 34 | 30 33 | syl5ibrcom | |- ( ( A e. RR /\ ( 0 -R A ) e. NN ) -> ( B = 0 -> ( A x. B ) = ( B x. A ) ) ) |
| 35 | 34 | imp | |- ( ( ( A e. RR /\ ( 0 -R A ) e. NN ) /\ B = 0 ) -> ( A x. B ) = ( B x. A ) ) |
| 36 | 26 35 | jaodan | |- ( ( ( A e. RR /\ ( 0 -R A ) e. NN ) /\ ( B e. NN \/ B = 0 ) ) -> ( A x. B ) = ( B x. A ) ) |
| 37 | 1 36 | sylan2b | |- ( ( ( A e. RR /\ ( 0 -R A ) e. NN ) /\ B e. NN0 ) -> ( A x. B ) = ( B x. A ) ) |