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Model Paper 10 — Maths STD 11 Science — Question

CBSE BoardEnglish MediumSTD 11 ScienceMathsModel Paper 101 Mark
MCQ
Mark the correct answer for $(1+ i )^{-1}=$ ?
  • A
    $\left(\frac{-1}{2}+\frac{1}{2} i\right)$
  • B
    (2 - 3i)
  • C
    $\left(\frac{1}{2}-\frac{1}{2} i\right)$
  • D
    (2 - i)
✓

Answer

(c) $\left(\frac{1}{2}-\frac{1}{2} i\right)$
Explanation: $(1+i)^{-1}=\frac{1}{(1+i)}=\frac{1}{(1+i)} \times \frac{(1-i)}{(1-i)}=\frac{(1-i)}{\left(1^2-i^2\right)}=\frac{(1-i)}{2}=\left(\frac{1}{2}-\frac{1}{2} i\right)$

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