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AP EAMCET · Maths · Complex Number

A complex number \(z\) among the following which satisfy \(z^3+27 i=0\) is

  1. A \((3 \sqrt{3}-3 i) / 2\)
  2. B \(-3 i\)
  3. C \((3 \sqrt{3}+3 i) / 2\)
  4. D \((-3 \sqrt{3}+3 i) / 2\)
Verified Solution

Answer & Solution

Correct Answer

(A) \((3 \sqrt{3}-3 i) / 2\)

Step-by-step Solution

Detailed explanation

Given, \(z^3+27 i=0\) \(\begin{aligned} & \Rightarrow \quad z^3-(3 i)^3=0 \\ & \Rightarrow \quad(z-3 i)\left(z^2+3 z i-9\right)=0\end{aligned}\) If \(\quad z-3 i=0 \Rightarrow z=3 i\) If \(z^2+3 z i-9=0\)…