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For what positive values of k, the quadratic . . .

Question : For what positive values of k, the quadratic equation 3x²–kx+3=0 has equal roots?

Doubts by Mehak

Solution : 

3x²–kx+3=0

a = 3
b = -k
c = 3

D = b²-4ac
D = (-k)²-4(3)(3)
D = k²-36
0 = k²-36 [∵ Roots are equal]
36 = k²
k = ±√36
k=
±6

But k≠-6

Hence, 

k=6