Q. 24

If the roots of 5x2 - kx + 1 = 0 are real and distinct then
A. –2√5 < k < 2√5

B. k > 2 √5 only

C. k < - 2√5 only

D. either k > 2 √5 or k < - 2√5

Answer :

Given that the roots of 5x2 - kx + 1 = 0 are real and distinct


a = 5 b = - k c = 1


D = b2 - 4ac > 0


= ( - k)2 - 4.5.1


= k2 - 20 > 0


k2 > 20


Roots are either

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