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Description: A complex number can be expressed in terms of two reals. Definition 10-1.1(v) of Gleason p. 130. Axiom 17 of 22 for real and complex numbers, justified by Theorem axcnre . For naming consistency, use cnre for new proofs. (New usage is discouraged.) (Contributed by NM, 9-May-1999)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | ax-cnre | ⊢ ( 𝐴 ∈ ℂ → ∃ 𝑥 ∈ ℝ ∃ 𝑦 ∈ ℝ 𝐴 = ( 𝑥 + ( i · 𝑦 ) ) ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 0 | cA | ⊢ 𝐴 | |
| 1 | cc | ⊢ ℂ | |
| 2 | 0 1 | wcel | ⊢ 𝐴 ∈ ℂ |
| 3 | vx | ⊢ 𝑥 | |
| 4 | cr | ⊢ ℝ | |
| 5 | vy | ⊢ 𝑦 | |
| 6 | 3 | cv | ⊢ 𝑥 |
| 7 | caddc | ⊢ + | |
| 8 | ci | ⊢ i | |
| 9 | cmul | ⊢ · | |
| 10 | 5 | cv | ⊢ 𝑦 |
| 11 | 8 10 9 | co | ⊢ ( i · 𝑦 ) |
| 12 | 6 11 7 | co | ⊢ ( 𝑥 + ( i · 𝑦 ) ) |
| 13 | 0 12 | wceq | ⊢ 𝐴 = ( 𝑥 + ( i · 𝑦 ) ) |
| 14 | 13 5 4 | wrex | ⊢ ∃ 𝑦 ∈ ℝ 𝐴 = ( 𝑥 + ( i · 𝑦 ) ) |
| 15 | 14 3 4 | wrex | ⊢ ∃ 𝑥 ∈ ℝ ∃ 𝑦 ∈ ℝ 𝐴 = ( 𝑥 + ( i · 𝑦 ) ) |
| 16 | 2 15 | wi | ⊢ ( 𝐴 ∈ ℂ → ∃ 𝑥 ∈ ℝ ∃ 𝑦 ∈ ℝ 𝐴 = ( 𝑥 + ( i · 𝑦 ) ) ) |