If the equation 9x2 + 6kx + 4 = o has equal roots, then the roots are both equal to ?
If roots of given equation are equal then D = b2 – 4ac = 0
(6k)2 – 4(9)(4) = 0
36k2 – 144 = 0
36k2 = 144
K2 = 4
K = 
2
Case 1 :- when k = 2
In equation 9x2 + 6 k x + 4 = 0
9x2 + 6(2) x + 4 = 0
9x2 + 12 x + 4 = 0
(3x)2 + 2 × 2 × 3x + (2)2 = 0
(3x + 2)2 = 0
3 x + 2 = 0
3x = – 2
X = – 
Case 2 :- when k = – 2
In equation 9x2 + 6kx + 4 = 0
9x2 + 6(– 2) x + 4 = 0
9x2 – 12 x + 4 = 0
(3x) 2 – 2 X 2 X 3x + (2)2 = 0
(3x – 2)2 = 0
3x – 2 = 0
3x = 2
X = 
So the roots of the given quadratic equation are 
3