Question 11 - CBSE Class 10 Sample Paper for 2025 Boards - Maths Standard - Solutions of Sample Papers for Class 10 Boards

Last updated at Sept. 17, 2024 by Teachoo

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Question 11 The roots of the quadratic equation 𝑥^2+𝑥−1=0 are (A) Irrational and distinct (B) not real (C) rational and distinct (D) real and equal x2 + x − 1 = 0 Comparing equation with ax2 + bx + c = 0 a = 1 , b = 1, c = −1 We know that , D = b2 – 4ac = (1)2 – 4 × 1 × (−1) = 1 + 4 = 5 Concept: D < 0 , no real roots D = O , two equal real roots D > 0, two distinct real roots Since D > 0 There are 2 distinct real roots Now using quadratic formula to find roots x = (− 𝑏 ± √𝐷)/2𝑎 Putting values x = (−1 ± √5)/(2 × 1) x = (−𝟏 ± √𝟓)/𝟐 Therefore, the root of the equation are x = (−𝟏 + √𝟓)/𝟐 & x = (−𝟏 − √𝟓)/𝟐 Thus, Roots are irrational Roots are distinct So, the correct answer is (A)

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Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 14 years. He provides courses for Maths, Science, Social Science, Physics, Chemistry, Computer Science at Teachoo.

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