Q20 of 227 Page 114

If x2 + 5kx + 16 = 0 has no real roots, then

Given: The quadratic equation and has no real roots.

Required: To find the value of k


Here,


b2–4ac<0 (∵ Quadratic equation has no real roots)


⇒ (5k)2–4(1)(16)<0


⇒ 25k2<64


⇒ k2<


Applying Square root on both sides


⇒ √k2 <


⇒


∴ The value of k is


∴ Correct Option is - Option (C)

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