Question

    Let a + b = 2c, then which of the following expressions

    is true?
    A a² + 2ac = b² + 2bc Correct Answer Incorrect Answer
    B a² – 2bc = b² – 2ac Correct Answer Incorrect Answer
    C a² + 2bc = b² + 2ac Correct Answer Incorrect Answer
    D a² – ac = b² – bc Correct Answer Incorrect Answer

    Solution

    Given (a + b = 2c), we can rewrite it as (a - c = c – b).  Square both sides:  [(a – c)2 = (c – b)2] [a2 – 2ac + c2 = b2 - 2bc + c2] Therefore, [a2 + 2bc = b2 + 2ac] 

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