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    Question

    A and B are the roots of equation x2 - 13x +

    k = 0. If A - B = 5, what is the value of k?
    A 26 Correct Answer Incorrect Answer
    B 40 Correct Answer Incorrect Answer
    C 36 Correct Answer Incorrect Answer
    D 42 Correct Answer Incorrect Answer

    Solution

    We know that the difference of roots is given by {√(b2 – 4ac)}/a, Here, a = 1, b = -13 and c = k Therefore, A – B = (√(b2 – 4ac))/a 5 = (√((-13)2 – 4 x 1 x k))/1 Squaring both the side we get, 25 = 169 – 4k 4k = 169 – 25 k = 144/4 = 36

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