Database
REAL AND COMPLEX NUMBERS
Elementary real and complex functions
Real and imaginary parts; conjugate
cjmulrcli
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cjmulvali
Metamath Proof Explorer
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Theorem
cjmulrcli
Description:
A complex number times its conjugate is real.
(Contributed by
NM
, 11-May-1999)
Ref
Expression
Hypothesis
recl.1
⊢
A
∈
ℂ
Assertion
cjmulrcli
⊢
A
⁢
A
‾
∈
ℝ
Proof
Step
Hyp
Ref
Expression
1
recl.1
⊢
A
∈
ℂ
2
cjmulrcl
⊢
A
∈
ℂ
→
A
⁢
A
‾
∈
ℝ
3
1
2
ax-mp
⊢
A
⁢
A
‾
∈
ℝ