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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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Question 20 Find the value(s) of k for which the quadratic equation x2 + 2√2 𝑘𝑥 + 18 = 0 has equal roots x2 + 2√2 𝑘𝑥 + 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 × 1 × 18 = 0 22 × (√2)^2× k2 – 72 = 0 4 × 2 × k2 = 72 8k2 = 72 k2 = 72/8 k2 = 9 k = ± √9 k = ± 3

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