Q. 8 A5.0( 3 Votes )

For what values of k, does the following quadratic equation has equal roots.

9x2 + 8kx + 16 = 0

Answer :

Since roots are equal


d=0 (1)


9x2 + 8kx + 16 = 0


d = b2 – 4ac


d = (8k)2 – 4 (9) (16)


From (1), d = 0


Equation will be:


0 = 64k2 – 576



k2 = 9


k = ±√9


k = 3, –3


values of k are –3, 3 .


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