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    Question

    If x – y = 1 and x2 + y2 = 41

    where x, y ≥ 0, then the value of x + y will be:
    A 6 Correct Answer Incorrect Answer
    B 7 Correct Answer Incorrect Answer
    C 9 Correct Answer Incorrect Answer
    D 8 Correct Answer Incorrect Answer

    Solution

    (x - y)² = x² - 2xy + y²  x - y = 1 and x2 + y2 = 41 (x - y)² = x² - 2xy + y²  1 = 41 - 2xy  xy = 20 now - (x + y)² = x² + 2xy + y² =41+2×20 (x + y)²=81 x+y =9.

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