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Metamath Proof Explorer
Theorem i2
Description: _i squared. (Contributed by NM, 6-May-1999)
|
|
Ref |
Expression |
|
Assertion |
i2 |
⊢ ( i ↑ 2 ) = - 1 |
Proof
| Step |
Hyp |
Ref |
Expression |
| 1 |
|
ax-icn |
⊢ i ∈ ℂ |
| 2 |
1
|
sqvali |
⊢ ( i ↑ 2 ) = ( i · i ) |
| 3 |
|
ixi |
⊢ ( i · i ) = - 1 |
| 4 |
2 3
|
eqtri |
⊢ ( i ↑ 2 ) = - 1 |