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| Mirrors > Home > ILE Home > Th. List > ax-i2m1 | Unicode version | ||
| Description: i-squared equals -1 (expressed as i-squared plus 1 is 0). Axiom for real and complex numbers, justified by Theorem axi2m1 7942. (Contributed by NM, 29-Jan-1995.) | 
| Ref | Expression | 
|---|---|
| ax-i2m1 | 
 | 
| Step | Hyp | Ref | Expression | 
|---|---|---|---|
| 1 | ci 7881 | 
. . . 4
 | |
| 2 | cmul 7884 | 
. . . 4
 | |
| 3 | 1, 1, 2 | co 5922 | 
. . 3
 | 
| 4 | c1 7880 | 
. . 3
 | |
| 5 | caddc 7882 | 
. . 3
 | |
| 6 | 3, 4, 5 | co 5922 | 
. 2
 | 
| 7 | cc0 7879 | 
. 2
 | |
| 8 | 6, 7 | wceq 1364 | 
1
 | 
| Colors of variables: wff set class | 
| This axiom is referenced by: 0cn 8018 ine0 8420 ixi 8610 inelr 8611 | 
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