Question

    If (x + y) = 6 and (x2 + y2) = 20,

    then the value of (x – y)2 is equal to:
    A 3 Correct Answer Incorrect Answer
    B 10 Correct Answer Incorrect Answer
    C 6 Correct Answer Incorrect Answer
    D 4 Correct Answer Incorrect Answer

    Solution

    (x + y)2 = x2 + y2 + 2xy Or, 2xy = 62 – 20 = 16 Then, (x – y) = x + y – 2xy = 20 – 16 = 4  

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