NDA Math Mock Test 03 – Question 45

Question:

A complex number is given by \(Z = \frac{1+2i}{1-(1-i)^2}\). What is the modulus of \(Z\)?

एक सम्मिश्र संख्या \(Z = \frac{1+2i}{1-(1-i)^2}\) द्वारा दी गई है। \(Z\) का मापांक क्या है?

Options:

  • 4
  • 2
  • 1
  • 1/2
  • 4
  • 2
  • 1
  • 1/2

Correct Answer: c)

Explanation:

Simplify the denominator:
\[(1 – i)^2 = 1 – 2i + i^2 = 1 – 2i – 1 = -2i\]
Denominator \(= 1 – (-2i) = 1 + 2i\).
Therefore:
\[Z = \frac{1 + 2i}{1 + 2i} = 1\]
The modulus is:
\[|Z| = |1| = 1\]
Hence, the correct option is (c).

हर को सरल करने पर:
\[(1 – i)^2 = 1 – 2i – 1 = -2i\]
हर \(= 1 – (-2i) = 1 + 2i\)।
अतः सम्मिश्र संख्या:
\[Z = \frac{1 + 2i}{1 + 2i} = 1\]
मापांक:
\[|Z| = |1| = 1\]
अतः सही विकल्प (c) है।

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