Q. 175.0( 2 Votes )

If the equation 9x2 + 6kx + 4 = 0 has equal roots then k = ?
A. 2 or 0

B. - 2 or 0

C. 2 or - 2

D. 0 only

Answer :

The equation 9x2 + 6kx + 4 = 0 has equal roots


a = 9 b = 6k c = 4


Then D = b2 - 4ac = 0


(6k)2 - 4.9.4 = 0


36k2 = 144


k2 = 4 taking square root both sides


k = 2 or k = - 2

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