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Description: An integer divided by the gcd of it and a nonzero integer is an integer. (Contributed by AV, 11-Jul-2021)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | divgcdz | |- ( ( A e. ZZ /\ B e. ZZ /\ B =/= 0 ) -> ( A / ( A gcd B ) ) e. ZZ ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | gcddvds | |- ( ( A e. ZZ /\ B e. ZZ ) -> ( ( A gcd B ) || A /\ ( A gcd B ) || B ) ) |
|
| 2 | 1 | 3adant3 | |- ( ( A e. ZZ /\ B e. ZZ /\ B =/= 0 ) -> ( ( A gcd B ) || A /\ ( A gcd B ) || B ) ) |
| 3 | 2 | simpld | |- ( ( A e. ZZ /\ B e. ZZ /\ B =/= 0 ) -> ( A gcd B ) || A ) |
| 4 | gcd2n0cl | |- ( ( A e. ZZ /\ B e. ZZ /\ B =/= 0 ) -> ( A gcd B ) e. NN ) |
|
| 5 | nnz | |- ( ( A gcd B ) e. NN -> ( A gcd B ) e. ZZ ) |
|
| 6 | nnne0 | |- ( ( A gcd B ) e. NN -> ( A gcd B ) =/= 0 ) |
|
| 7 | 5 6 | jca | |- ( ( A gcd B ) e. NN -> ( ( A gcd B ) e. ZZ /\ ( A gcd B ) =/= 0 ) ) |
| 8 | 4 7 | syl | |- ( ( A e. ZZ /\ B e. ZZ /\ B =/= 0 ) -> ( ( A gcd B ) e. ZZ /\ ( A gcd B ) =/= 0 ) ) |
| 9 | simp1 | |- ( ( A e. ZZ /\ B e. ZZ /\ B =/= 0 ) -> A e. ZZ ) |
|
| 10 | df-3an | |- ( ( ( A gcd B ) e. ZZ /\ ( A gcd B ) =/= 0 /\ A e. ZZ ) <-> ( ( ( A gcd B ) e. ZZ /\ ( A gcd B ) =/= 0 ) /\ A e. ZZ ) ) |
|
| 11 | 8 9 10 | sylanbrc | |- ( ( A e. ZZ /\ B e. ZZ /\ B =/= 0 ) -> ( ( A gcd B ) e. ZZ /\ ( A gcd B ) =/= 0 /\ A e. ZZ ) ) |
| 12 | dvdsval2 | |- ( ( ( A gcd B ) e. ZZ /\ ( A gcd B ) =/= 0 /\ A e. ZZ ) -> ( ( A gcd B ) || A <-> ( A / ( A gcd B ) ) e. ZZ ) ) |
|
| 13 | 11 12 | syl | |- ( ( A e. ZZ /\ B e. ZZ /\ B =/= 0 ) -> ( ( A gcd B ) || A <-> ( A / ( A gcd B ) ) e. ZZ ) ) |
| 14 | 3 13 | mpbid | |- ( ( A e. ZZ /\ B e. ZZ /\ B =/= 0 ) -> ( A / ( A gcd B ) ) e. ZZ ) |