4-1.Complex numbers
easy

यदि $z$ एक सम्मिश्र संख्या हो, तो $(\overline {{z^{ - 1}}} )(\overline z ) = $

A

$1$

B

$-1$

C

$0$

D

इनमें से कोई नहीं

Solution

(a) माना  $z = x + iy,\overline z  = x – iy$ एवं ${z^{ – 1}} = \frac{1}{{x + iy}}$

$⇒ (\overline {{z^{ – 1}}} ) = \frac{{x + iy}}{{{x^2} + {y^2}}}$; 

$\therefore $$(\overline {{z^{ – 1}}} )\,\bar z = \frac{{x + iy}}{{{x^2} + {y^2}}}(x – iy) = 1$

Standard 11
Mathematics

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