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    Question

    When a number is added to its multiple of 5 and its

    square, the sum of these three numbers is 91. Find the number.
    A 9 Correct Answer Incorrect Answer
    B 11 Correct Answer Incorrect Answer
    C 7 Correct Answer Incorrect Answer
    D 6 Correct Answer Incorrect Answer

    Solution

    Let the number is ‘x’ Given: A number is added to its multiple of 5 and its square, the sum of these three numbers is 91. => x + 5x + x = 91 => x + 6x - 91 = 0 => x + 13x – 7x - 91 = 0 => x(x + 13) – 7(x + 13) = 0 => (x + 13)(x - 7) = 0 So, x + 13 = 0 and x - 7 = 0 x = - 13 and x = 7 There are two values of x = -13, 7 But we take positive value. Hence, “7” is the correct answer.

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