Database
REAL AND COMPLEX NUMBERS
Elementary real and complex functions
Real and imaginary parts; conjugate
reim0bi
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rerebi
Metamath Proof Explorer
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Theorem
reim0bi
Description:
A number is real iff its imaginary part is 0.
(Contributed by
NM
, 29-May-1999)
Ref
Expression
Hypothesis
recl.1
⊢
A
∈
ℂ
Assertion
reim0bi
⊢
A
∈
ℝ
↔
ℑ
⁡
A
=
0
Proof
Step
Hyp
Ref
Expression
1
recl.1
⊢
A
∈
ℂ
2
reim0b
⊢
A
∈
ℂ
→
A
∈
ℝ
↔
ℑ
⁡
A
=
0
3
1
2
ax-mp
⊢
A
∈
ℝ
↔
ℑ
⁡
A
=
0