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Find the value(s) of k for which the quadratic equation

x 2 + 2√2 kx + 18 = 0 has equal roots

Find the value(s) of k for which quadratic equation x2 + 2√2 kx + 18

Question 20 - CBSE Class 10 Sample Paper for 2020 Boards - Maths Standard - Part 2

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Transcript

Question 20 Find the value(s) of k for which the quadratic equation x2 + 2√2 π‘˜π‘₯ + 18 = 0 has equal roots x2 + 2√2 π‘˜π‘₯ + 18 = 0 Comparing equation with ax2 + bx + c = 0 a = 1, b = 2√2k , c = 18 Since the equation has 2 equal roots, D = 0 b2 – 4ac = 0 Putting values (2√2k)2 – 4 Γ— 1 Γ— 18 = 0 22 Γ— (√2)^2Γ— k2 – 72 = 0 4 Γ— 2 Γ— k2 = 72 8k2 = 72 k2 = 72/8 k2 = 9 k = Β± √9 k = Β± 3

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Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 13 years. He provides courses for Maths, Science, Social Science, Physics, Chemistry, Computer Science at Teachoo.