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For what values of k are the roots of the quadratic equation 3x2 + 2kx + 27 = 0 real and equal?
Given: 3x2 + 2kx + 27 = 0
Comparing with standard quadratic equation ax2 + bx + c = 0
a = 3 b = 2k c = 27
Given that the roots of equation are real and equal
Thus D = 0
Discriminant D = b2 – 4ac = 0
(2k)2 – 4.3.27 = 0
4k2 – 324 = 0
4k2 = 324
k2 = 81 taking square root on both sides
k = 9 or k = – 9
The values of k are 9, – 9 for which roots of the quadratic equation are real and equal.