Misc 9 - Solve 21x2 - 28x + 10 = 0 - Chapter 5 NCERT - Miscellaneous

Misc 9 - Chapter 5 Class 11 Complex Numbers - Part 2

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Transcript

Question 5 Solve the equation 21𝑥2 – 28𝑥 + 10 = 0 21𝑥2 – 28𝑥 + 10 = 0 The Above equation of the form 𝑎𝑥2 + 𝑏𝑥 + 𝑐 = 0 Where a = 21, b = –28, and c = 10 𝑥 = (−𝑏 ± √( 𝑏^2 − 4𝑎𝑐 ))/2𝑎 𝑥 = (− ( − 28) ± √((−28)^2 −4 × 21 ×10))/(2 × 21) = (28 ± √(784 − 840))/42 = (28 ± √(−56))/42 = (28 ± √(− 14 ×4 ))/42 = (28 ± 2√(− 14))/42 = (2 [14 ± √(− 14) ])/42 = (2 [ 14 ± √(− 14) ])/(2 × 21) = ( [ 14 ± √(− 14) ] )/21 = ( 14 ± √(− 1 × 14) )/21 = ( 14 ± √(− 1) ×√14)/21 = ( 14 ± √14 𝑖)/21 Thus, 𝑥 = ( 14 ± √14 𝑖)/21

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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.