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JEE Main 202622 JanuaryEvening Shift
Exam
JEE Main
Year
2026
Date
22 January
Shift
Evening Shift
Subject
Mathematics
Chapter
Complex Number

JEE Main 2026 · 22 January · Evening Shift · Mathematics · Complex Number

Let S=\ z ∈ ℂ: 4 z^ 2 + z =0\ . Then ∑_ z ∈ S |z|^ 2 is equal to:

Let S={z∈C:4z2+zˉ=0}S=\left\{z \in \mathbb{C}: 4 z^{2}+\bar{z}=0\right\}. Then ∑z∈S∣z∣2\sum_{z \in S}|z|^{2} is equal to:

Options

  1. A564\frac{5}{64}
  2. B116\frac{1}{16}
  3. C316\frac{3}{16}
  4. D764\frac{7}{64}

Correct answer

C. 316\frac{3}{16}

Step-by-step solution

Let z=x+iyz=x+iy. From 4z2+zˉ=04z^2+\bar{z}=0, separating real and imaginary parts:
Real: 4x2−4y2+x=04x^2-4y^2+x=0, Imaginary: y(8x−1)=0y(8x-1)=0.
Case 1: y=0y=0
⇒x(4x+1)=0\Rightarrow x(4x+1)=0
⇒z=0\Rightarrow z=0 or z=−14z=-\frac{1}{4}.
Case 2: x=18x=\frac{1}{8}
⇒116−4y2+18=0\Rightarrow \frac{1}{16}-4y^2+\frac{1}{8}=0
⇒y2=364\Rightarrow y^2=\frac{3}{64}.
So ∣z∣2=164+364=116|z|^2=\frac{1}{64}+\frac{3}{64}=\frac{1}{16}.
∑∣z∣2=0+116+116+116=316\sum|z|^2=0+\frac{1}{16}+\frac{1}{16}+\frac{1}{16}=\frac{3}{16}
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