JEE Main 2020 · MathsMultiple choiceSingle correctMediumMulti-step

JEE Main 8 January 2020, Shift 1, Maths Q52

Question 52 of 75 in this shift, Maths question 2 of 25, Section A.

If the equation,

x^2+bx+45=0

(

b\in R

) has conjugate complex roots and they satisfy

|z+1|=2\sqrt{10}

, then :

(1) $b^2+b=12$
(2) $b^2-b=42$
(3) $b^2-b=30$ Official answer
(4) $b^2+b=72$

Official answer

Option 3

NTA final key (Jan 2020).

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

Same idea in other shifts

Asked 4× in all

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31 Jan 2024, Shift 1 · Q7Let $a$ be the sum of all coefficients in the expansion of $(1-2x+2x^2)^{2023}(3-4x^2+2x^3)^{2024}$ and…HardSingle 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 42 of the 174 JEE Main shifts held from 2017 to 2026.