Question

    The equations 6x + my + 18 = 0 and 9x + 21y + 27 = 0

    have a unique solution. Which of the following statements is definitely true?
    A m ≠ 7 Correct Answer Incorrect Answer
    B m = 14 Correct Answer Incorrect Answer
    C m = 7 Correct Answer Incorrect Answer
    D m ≠ 14 Correct Answer Incorrect Answer

    Solution

    If two equations a1x + b1y + c1 = 0 and a2x + b2y + c2 = 0 have a unique solution, then (a1/a2) ≠ (b1/b2) So, (6/9) ≠ (m/21) Or, 'm' ≠ 14

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