JEE Main 2025 · MathsNumerical answerNumerical valueMediumMulti-step

JEE Main 4 April 2025, Shift 2, Maths Q21

Question 21 of 75 in this shift, Maths question 21 of 25, Section B.

\alpha

is a root of the equation

x^2+x+1=0

and

\sum_{k=1}^{n}\left(\alpha^k+\frac{1}{\alpha^k}\right)^2=20

, then n is equal to ____________.

Official answer

NTA final key.

Chapter: Complex Numbers and Quadratic Equations
Topic: Roots of Unity
Idea tested: Cyclic Powers of Omega Modulo 3

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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 42 of the 174 JEE Main shifts held from 2017 to 2026.