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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 ∈ ℤ ∧ 𝐵 ∈ ℤ ∧ 𝐵 ≠ 0 ) → ( 𝐴 / ( 𝐴 gcd 𝐵 ) ) ∈ ℤ ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | gcddvds | ⊢ ( ( 𝐴 ∈ ℤ ∧ 𝐵 ∈ ℤ ) → ( ( 𝐴 gcd 𝐵 ) ∥ 𝐴 ∧ ( 𝐴 gcd 𝐵 ) ∥ 𝐵 ) ) | |
| 2 | 1 | 3adant3 | ⊢ ( ( 𝐴 ∈ ℤ ∧ 𝐵 ∈ ℤ ∧ 𝐵 ≠ 0 ) → ( ( 𝐴 gcd 𝐵 ) ∥ 𝐴 ∧ ( 𝐴 gcd 𝐵 ) ∥ 𝐵 ) ) |
| 3 | 2 | simpld | ⊢ ( ( 𝐴 ∈ ℤ ∧ 𝐵 ∈ ℤ ∧ 𝐵 ≠ 0 ) → ( 𝐴 gcd 𝐵 ) ∥ 𝐴 ) |
| 4 | gcd2n0cl | ⊢ ( ( 𝐴 ∈ ℤ ∧ 𝐵 ∈ ℤ ∧ 𝐵 ≠ 0 ) → ( 𝐴 gcd 𝐵 ) ∈ ℕ ) | |
| 5 | nnz | ⊢ ( ( 𝐴 gcd 𝐵 ) ∈ ℕ → ( 𝐴 gcd 𝐵 ) ∈ ℤ ) | |
| 6 | nnne0 | ⊢ ( ( 𝐴 gcd 𝐵 ) ∈ ℕ → ( 𝐴 gcd 𝐵 ) ≠ 0 ) | |
| 7 | 5 6 | jca | ⊢ ( ( 𝐴 gcd 𝐵 ) ∈ ℕ → ( ( 𝐴 gcd 𝐵 ) ∈ ℤ ∧ ( 𝐴 gcd 𝐵 ) ≠ 0 ) ) |
| 8 | 4 7 | syl | ⊢ ( ( 𝐴 ∈ ℤ ∧ 𝐵 ∈ ℤ ∧ 𝐵 ≠ 0 ) → ( ( 𝐴 gcd 𝐵 ) ∈ ℤ ∧ ( 𝐴 gcd 𝐵 ) ≠ 0 ) ) |
| 9 | simp1 | ⊢ ( ( 𝐴 ∈ ℤ ∧ 𝐵 ∈ ℤ ∧ 𝐵 ≠ 0 ) → 𝐴 ∈ ℤ ) | |
| 10 | df-3an | ⊢ ( ( ( 𝐴 gcd 𝐵 ) ∈ ℤ ∧ ( 𝐴 gcd 𝐵 ) ≠ 0 ∧ 𝐴 ∈ ℤ ) ↔ ( ( ( 𝐴 gcd 𝐵 ) ∈ ℤ ∧ ( 𝐴 gcd 𝐵 ) ≠ 0 ) ∧ 𝐴 ∈ ℤ ) ) | |
| 11 | 8 9 10 | sylanbrc | ⊢ ( ( 𝐴 ∈ ℤ ∧ 𝐵 ∈ ℤ ∧ 𝐵 ≠ 0 ) → ( ( 𝐴 gcd 𝐵 ) ∈ ℤ ∧ ( 𝐴 gcd 𝐵 ) ≠ 0 ∧ 𝐴 ∈ ℤ ) ) |
| 12 | dvdsval2 | ⊢ ( ( ( 𝐴 gcd 𝐵 ) ∈ ℤ ∧ ( 𝐴 gcd 𝐵 ) ≠ 0 ∧ 𝐴 ∈ ℤ ) → ( ( 𝐴 gcd 𝐵 ) ∥ 𝐴 ↔ ( 𝐴 / ( 𝐴 gcd 𝐵 ) ) ∈ ℤ ) ) | |
| 13 | 11 12 | syl | ⊢ ( ( 𝐴 ∈ ℤ ∧ 𝐵 ∈ ℤ ∧ 𝐵 ≠ 0 ) → ( ( 𝐴 gcd 𝐵 ) ∥ 𝐴 ↔ ( 𝐴 / ( 𝐴 gcd 𝐵 ) ) ∈ ℤ ) ) |
| 14 | 3 13 | mpbid | ⊢ ( ( 𝐴 ∈ ℤ ∧ 𝐵 ∈ ℤ ∧ 𝐵 ≠ 0 ) → ( 𝐴 / ( 𝐴 gcd 𝐵 ) ) ∈ ℤ ) |