Q. 24

# If the roots of 5x2 - kx + 1 = 0 are real and distinct thenA. –2√5 < k < 2√5B. k > 2 √5 onlyC. k < - 2√5 onlyD. either k > 2 √5 or k < - 2√5

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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