JEE Main 2021 · MathsMultiple choiceSingle correctMediumMulti-step

JEE Main 25 February 2021, Shift 1, Maths Q76

Question 76 of 90 in this shift, Maths question 16 of 30, Section A.

The coefficients a, b and c of the quadratic equation,

ax^2 + bx + c = 0

are obtained by throwing a dice three times. The probability that this equation has equal roots is :

(1) $\frac{1}{36}$
(2) $\frac{1}{54}$
(3) $\frac{1}{72}$
(4) $\frac{5}{216}$ Official answer

Official answer

Option 4

NTA final key.

Chapter: Probability
Topic: Quadratic Roots
Idea tested: Nature of Roots

Same idea in other shifts

Asked 9× in all

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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.