JEE Main 2022 · MathsNumerical answerNumerical valueHardMulti-step

JEE Main 26 June 2022, Shift 2, Maths Q23

Question 23 of 90 in this shift, Maths question 23 of 30, Section B.

z^2 + z + 1 = 0

z \in \mathbb{C}

, then

\left|\sum_{n=1}^{15}\left(z^n + (-1)^n \frac{1}{z^n}\right)^2\right|

is equal to ______.

Official answer

NTA final key.

Chapter: Complex Numbers and Quadratic Equations
Topic: Roots of Unity
Idea tested: Roots of z^2 + z + 1 = 0

Same idea in other shifts

Asked 2× in all

30 Jan 2024, Shift 2 · Q2If $z$ is a complex number, then the number of common roots of the equations $z^{1985} + z^{100} + 1 = 0$ and $z^3 + 2z^2 + 2z + 1 = 0$ ,…MediumSingle correct

Question text from the official JEE Main paper published by NTA; answer from the final answer key. Chapter, topic and idea tags, difficulty and skill are Lumi’s. Lumi analyses 108 of the 174 JEE Main shifts held from 2017 to 2026.