kx (3x - 4) + 4 = 03kx2 + 4kx + 4 = 0a = 3kb = -4kc = 4D = 0 (Since Roots are equal)b2 – 4ac = 0∴ (-4k)2 – 4(3k)(4) = 016 k2 – 48k = 016 k(k – 3) = 016 k = 0 or k – 3 = 0k = 0 or k = 3As coefficient of x2 can’t be zero so, Rejecting k = 0 and,∴ k = 3

Q. 135.0( 1 Vote )

Find the value of

Class 10th Mathematics - Board Papers All India - 2012

Answer :

kx (3x - 4) + 4 = 0

3kx² + 4kx + 4 = 0

a = 3k

b = -4k

c = 4

D = 0 (Since Roots are equal)

b² – 4ac = 0

∴ (-4k)² – 4(3k)(4) = 0

16 k² – 48k = 0

16 k(k – 3) = 0

16 k = 0 or k – 3 = 0

k = 0 or k = 3

As coefficient of x² can’t be zero so, Rejecting k = 0 and,

∴ k = 3

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