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Description: The modulo operation is periodic. (Contributed by NM, 12-Nov-2008)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | modcyc2 | |- ( ( A e. RR /\ B e. RR+ /\ N e. ZZ ) -> ( ( A - ( B x. N ) ) mod B ) = ( A mod B ) ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | recn | |- ( A e. RR -> A e. CC ) |
|
| 2 | rpcn | |- ( B e. RR+ -> B e. CC ) |
|
| 3 | zcn | |- ( N e. ZZ -> N e. CC ) |
|
| 4 | mulneg1 | |- ( ( N e. CC /\ B e. CC ) -> ( -u N x. B ) = -u ( N x. B ) ) |
|
| 5 | 4 | ancoms | |- ( ( B e. CC /\ N e. CC ) -> ( -u N x. B ) = -u ( N x. B ) ) |
| 6 | mulcom | |- ( ( B e. CC /\ N e. CC ) -> ( B x. N ) = ( N x. B ) ) |
|
| 7 | 6 | negeqd | |- ( ( B e. CC /\ N e. CC ) -> -u ( B x. N ) = -u ( N x. B ) ) |
| 8 | 5 7 | eqtr4d | |- ( ( B e. CC /\ N e. CC ) -> ( -u N x. B ) = -u ( B x. N ) ) |
| 9 | 8 | 3adant1 | |- ( ( A e. CC /\ B e. CC /\ N e. CC ) -> ( -u N x. B ) = -u ( B x. N ) ) |
| 10 | 9 | oveq2d | |- ( ( A e. CC /\ B e. CC /\ N e. CC ) -> ( A + ( -u N x. B ) ) = ( A + -u ( B x. N ) ) ) |
| 11 | mulcl | |- ( ( B e. CC /\ N e. CC ) -> ( B x. N ) e. CC ) |
|
| 12 | negsub | |- ( ( A e. CC /\ ( B x. N ) e. CC ) -> ( A + -u ( B x. N ) ) = ( A - ( B x. N ) ) ) |
|
| 13 | 11 12 | sylan2 | |- ( ( A e. CC /\ ( B e. CC /\ N e. CC ) ) -> ( A + -u ( B x. N ) ) = ( A - ( B x. N ) ) ) |
| 14 | 13 | 3impb | |- ( ( A e. CC /\ B e. CC /\ N e. CC ) -> ( A + -u ( B x. N ) ) = ( A - ( B x. N ) ) ) |
| 15 | 10 14 | eqtr2d | |- ( ( A e. CC /\ B e. CC /\ N e. CC ) -> ( A - ( B x. N ) ) = ( A + ( -u N x. B ) ) ) |
| 16 | 1 2 3 15 | syl3an | |- ( ( A e. RR /\ B e. RR+ /\ N e. ZZ ) -> ( A - ( B x. N ) ) = ( A + ( -u N x. B ) ) ) |
| 17 | 16 | oveq1d | |- ( ( A e. RR /\ B e. RR+ /\ N e. ZZ ) -> ( ( A - ( B x. N ) ) mod B ) = ( ( A + ( -u N x. B ) ) mod B ) ) |
| 18 | znegcl | |- ( N e. ZZ -> -u N e. ZZ ) |
|
| 19 | modcyc | |- ( ( A e. RR /\ B e. RR+ /\ -u N e. ZZ ) -> ( ( A + ( -u N x. B ) ) mod B ) = ( A mod B ) ) |
|
| 20 | 18 19 | syl3an3 | |- ( ( A e. RR /\ B e. RR+ /\ N e. ZZ ) -> ( ( A + ( -u N x. B ) ) mod B ) = ( A mod B ) ) |
| 21 | 17 20 | eqtrd | |- ( ( A e. RR /\ B e. RR+ /\ N e. ZZ ) -> ( ( A - ( B x. N ) ) mod B ) = ( A mod B ) ) |