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STD 11 - 4.1 complex nubers — Maths STD 11 Science — Question

CBSE BoardEnglish MediumSTD 11 ScienceMathsSTD 11 - 4.1 complex nubers1 Mark
MCQ
$(z + a)(\bar z + a)$, where $a$ is real, is equivalent to
  • A
    $|z - a|$
  • B
    ${z^2} + {a^2}$
  • ✓
    $|z + a{|^2}$
  • D
    None of these
✓

Answer

Correct option: C.
$|z + a{|^2}$
c
(c) As we know if $a$ is real, then $a = \overline a $
 $(z + a)(\overline z + a) = (z + a)(\overline z + \overline a ) = (z + a)(\overline {z + a} )$ $ = |z + a{|^2}$

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