Description: A complex number times its conjugate is nonnegative. (Contributed by NM, 28-May-1999)
| Ref | Expression | ||
|---|---|---|---|
| Hypothesis | recl.1 | ⊢ 𝐴 ∈ ℂ | |
| Assertion | cjmulge0i | ⊢ 0 ≤ ( 𝐴 · ( ∗ ‘ 𝐴 ) ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | recl.1 | ⊢ 𝐴 ∈ ℂ | |
| 2 | cjmulge0 | ⊢ ( 𝐴 ∈ ℂ → 0 ≤ ( 𝐴 · ( ∗ ‘ 𝐴 ) ) ) | |
| 3 | 1 2 | ax-mp | ⊢ 0 ≤ ( 𝐴 · ( ∗ ‘ 𝐴 ) ) |