Multiple Choice Question (MCQ)

What is the first term a_1 and the common ratio r of the following geometric sequence if the second, third and fourth terms are: -2, -1, -\dfrac{1}{2} ?

  1. a_1 = -4 and r = \dfrac{1}{2}

  2. ×

    a_1 = 4 and r = \dfrac{1}{2}

  3. ×

    a_1 = \dfrac{1}{2} and r = -4

  4. ×

    a_1 = -4 and r = -\dfrac{1}{2}

Collected in the board: Geometric sequence

Steven Zheng posted 1 month ago


Answer

  1. The common ratio r = \dfrac{-1}{-2} = \dfrac{1}{2}

    \dfrac{a_2}{a_1} = r


    Therefore,

    a_1 = \dfrac{a_2}{r} = \dfrac{-2}{1/2}=-4

Steven Zheng posted 1 month ago

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