Question

    If 4x + y = 18 and xy = - 10, what is the value of 4x -

    y?
    A 28 Correct Answer Incorrect Answer
    B 26 Correct Answer Incorrect Answer
    C 24 Correct Answer Incorrect Answer
    D 22 Correct Answer Incorrect Answer

    Solution

    4x + y = 18 and xy = -10
    (4x - y) 2  = (4x + y) 2  - 4(4x)(y)
    (4x - y) 2  = (18) 2  - 16 (-10)
    (4x - y) 2  = 22 2
    4x - y = 22

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