JEE Main 2020 · MathsMultiple choiceSingle correctMediumCalculation

JEE Main 4 September 2020, Shift 2, Maths Q53

Question 53 of 75 in this shift, Maths question 3 of 25.

If a and b are real numbers such that

(2+\alpha)^4 = a + b\alpha

, where

\alpha = \frac{-1+i\sqrt{3}}{2}

, then

a+b

is equal to :

(1) $9$ Official answer
(2) $24$
(3) $33$
(4) $57$

Official answer

Option 1

NTA final key (Sep 2020).

Chapter: Complex Numbers and Quadratic Equations
Topic: Roots of Unity
Idea tested: Cube Roots of Unity

Same topic in other shifts

All Roots of Unity questions

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