Question 5 - Quadaratic equation - Chapter 4 Class 11 Complex Numbers

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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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Question 5 Solve the equation 21š‘„2 ā€“ 28š‘„ + 10 = 0 21š‘„2 ā€“ 28š‘„ + 10 = 0 The Above equation of the form š‘Žš‘„2 + š‘š‘„ + š‘ = 0 Where a = 21, b = ā€“28, and c = 10 š‘„ = (āˆ’š‘ Ā± āˆš( š‘^2 āˆ’ 4š‘Žš‘ ))/2š‘Ž š‘„ = (āˆ’ ( āˆ’ 28) Ā± āˆš((āˆ’28)^2 āˆ’4 Ɨ 21 Ɨ10))/(2 Ɨ 21) = (28 Ā± āˆš(784 āˆ’ 840))/42 = (28 Ā± āˆš(āˆ’56))/42 = (28 Ā± āˆš(āˆ’ 14 Ɨ4 ))/42 = (28 Ā± 2āˆš(āˆ’ 14))/42 = (2 [14 Ā± āˆš(āˆ’ 14) ])/42 = (2 [ 14 Ā± āˆš(āˆ’ 14) ])/(2 Ɨ 21) = ( [ 14 Ā± āˆš(āˆ’ 14) ] )/21 = ( 14 Ā± āˆš(āˆ’ 1 Ɨ 14) )/21 = ( 14 Ā± āˆš(āˆ’ 1) Ɨāˆš14)/21 = ( 14 Ā± āˆš14 š‘–)/21 Thus, š‘„ = ( 14 Ā± āˆš14 š‘–)/21

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