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Description: If the difference between two numbers is zero, they are equal. (Contributed by Mario Carneiro, 27-May-2016)
| Ref | Expression | ||
|---|---|---|---|
| Hypotheses | negidd.1 | ⊢ ( 𝜑 → 𝐴 ∈ ℂ ) | |
| pncand.2 | ⊢ ( 𝜑 → 𝐵 ∈ ℂ ) | ||
| subeq0d.3 | ⊢ ( 𝜑 → ( 𝐴 − 𝐵 ) = 0 ) | ||
| Assertion | subeq0d | ⊢ ( 𝜑 → 𝐴 = 𝐵 ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | negidd.1 | ⊢ ( 𝜑 → 𝐴 ∈ ℂ ) | |
| 2 | pncand.2 | ⊢ ( 𝜑 → 𝐵 ∈ ℂ ) | |
| 3 | subeq0d.3 | ⊢ ( 𝜑 → ( 𝐴 − 𝐵 ) = 0 ) | |
| 4 | subeq0 | ⊢ ( ( 𝐴 ∈ ℂ ∧ 𝐵 ∈ ℂ ) → ( ( 𝐴 − 𝐵 ) = 0 ↔ 𝐴 = 𝐵 ) ) | |
| 5 | 1 2 4 | syl2anc | ⊢ ( 𝜑 → ( ( 𝐴 − 𝐵 ) = 0 ↔ 𝐴 = 𝐵 ) ) |
| 6 | 3 5 | mpbid | ⊢ ( 𝜑 → 𝐴 = 𝐵 ) |