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The coefficients a, b, c in the quadratic equation ax 2 + bx + c = 0 are chosen from the set {1, 2, 3, 4, 5, 6, 7, 8}. The probability of this equation having repeated roots is :

1. 256 3
2. 128 1
3. 64 1
4. 128 3

Correct answer: 64 1

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