Q. 145.0( 1 Vote )

# Mark the Correct alternative in the following:The values of k for which is quadratic equation has real and equal roots areA. -11, -3B. 5, 7C. 5, -7D. None of these

given kx2 + 1 = kx + 3x – 11x2

x2(k+11) – x(k + 3) + 1 = 0

as the roots are real and equal then the discriminant is equal to zero.

D = b2 – 4ac = 0

(k+3)2 – 4 (k+11) (1) = 0

K2 + 9 + 6k – 4k – 44 = 0

K2 + 2k – 35 = 0

(k-5) (k+7) = 0

K = 5, -7.

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