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