JEE Main 2021 · MathsMultiple choiceSingle correctEasyApplication

JEE Main 25 February 2021, Shift 2, Maths Q69

Question 69 of 90 in this shift, Maths question 9 of 30, Section A.

\alpha, \beta \in \mathbf{R}

are such that

1 - 2i

(here

i^2 = -1

) is a root of

z^2 + \alpha z + \beta = 0

, then

(\alpha - \beta)

is equal to :

(1) $3$
(2) $-3$
(3) $7$
(4) $-7$ Official answer

Official answer

Option 4

NTA final key.

Chapter: Complex Numbers and Quadratic Equations
Topic: Quadratic Roots
Idea tested: Complex Conjugate Roots

Same idea in other shifts

Asked 5× in all

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8 Jan 2020, Shift 1 · Q52If the equation, $x^2+bx+45=0$ ( $b\in R$ ) has conjugate complex roots and they satisfy $|z+1|=2\sqrt{10}$ , then :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.