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JEE Mains · Maths · STD 11 - 4.1 complex nubers

माना सम्मिश्र संख्या \(\mathrm{z}=\mathrm{x}+\) iy के लिए \(\frac{2 z-3 i}{2 z+i}\) मात्र काल्पनिक है। यदि \(\mathrm{x}+\mathrm{y}^2=0\) है, तो \(\mathrm{y}^4+\mathrm{y}^2-\mathrm{y}\) बराबर हैं :

  1. A \(\frac{3}{2}\)
  2. B \(\frac{4}{3}\)
  3. C \(\frac{2}{3}\)
  4. D \(\frac{3}{4}\)
Verified Solution

Answer & Solution

Correct Answer

(D) \(\frac{3}{4}\)

Step-by-step Solution

Detailed explanation

\(\frac{2 z-3 i}{2 z+i}\) is purely imaginary \(\therefore \frac{2 z-3 i}{2 z+i}+\frac{2 \bar{z}+3 i}{2 \bar{z}-i}=0\) \(z=x+i y\) \(\Rightarrow 4 x^2+4 y^2-4 y-3=0\) Given that \(x+y^2=0\) \(y^4+y^2-y=3 / 4\)
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