Step | Hyp | Ref
| Expression |
1 | | recexnq 7331 |
. 2
⊢ (𝐴 ∈ Q →
∃𝑦(𝑦 ∈ Q ∧ (𝐴
·Q 𝑦) =
1Q)) |
2 | | recmulnqg 7332 |
. . . . . 6
⊢ ((𝐴 ∈ Q ∧
𝑦 ∈ Q)
→ ((*Q‘𝐴) = 𝑦 ↔ (𝐴 ·Q 𝑦) =
1Q)) |
3 | 2 | biimpar 295 |
. . . . 5
⊢ (((𝐴 ∈ Q ∧
𝑦 ∈ Q)
∧ (𝐴
·Q 𝑦) = 1Q) →
(*Q‘𝐴) = 𝑦) |
4 | | eleq1a 2238 |
. . . . . 6
⊢ (𝑦 ∈ Q →
((*Q‘𝐴) = 𝑦 →
(*Q‘𝐴) ∈ Q)) |
5 | 4 | ad2antlr 481 |
. . . . 5
⊢ (((𝐴 ∈ Q ∧
𝑦 ∈ Q)
∧ (𝐴
·Q 𝑦) = 1Q) →
((*Q‘𝐴) = 𝑦 →
(*Q‘𝐴) ∈ Q)) |
6 | 3, 5 | mpd 13 |
. . . 4
⊢ (((𝐴 ∈ Q ∧
𝑦 ∈ Q)
∧ (𝐴
·Q 𝑦) = 1Q) →
(*Q‘𝐴) ∈ Q) |
7 | 6 | expl 376 |
. . 3
⊢ (𝐴 ∈ Q →
((𝑦 ∈ Q
∧ (𝐴
·Q 𝑦) = 1Q) →
(*Q‘𝐴) ∈ Q)) |
8 | 7 | exlimdv 1807 |
. 2
⊢ (𝐴 ∈ Q →
(∃𝑦(𝑦 ∈ Q ∧
(𝐴
·Q 𝑦) = 1Q) →
(*Q‘𝐴) ∈ Q)) |
9 | 1, 8 | mpd 13 |
1
⊢ (𝐴 ∈ Q →
(*Q‘𝐴) ∈ Q) |