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Find the 7th term of the geometric series 1 + (2)/(sqrt(3)) + (4)/(3) + (8)/(3sqrt(3)) + and determine if its sum to infinity exists.

Mathematics

ScanSolve AI Answer

Answer

C\text{C}

D\text{D}

Step-by-step solution

5 steps
  1. Identify the type of series and its properties for question 5.

    The given series is 1+23+43+833+…1 + \frac{2}{\sqrt{3}} + \frac{4}{3} + \frac{8}{3\sqrt{3}} + \dots.
    This is a geometric series.
    The first term is a=1a = 1.
    The common ratio rr is found by dividing the second term by the first term:

    r=231=23r = \frac{\frac{2}{\sqrt{3}}}{1} = \frac{2}{\sqrt{3}}
  2. Calculate the 7th term using the formula for the nn-th term of a geometric series.

    The formula for the nn-th term of a geometric series is Tn=a⋅rn−1T_n = a \cdot r^{n-1}.
    For the 7th term, n=7n=7:

    T7=1⋅(23)7−1T_7 = 1 \cdot \left(\frac{2}{\sqrt{3}}\right)^{7-1} T7=(23)6T_7 = \left(\frac{2}{\sqrt{3}}\right)^6 T7=26(3)6T_7 = \frac{2^6}{(\sqrt{3})^6} T7=6433T_7 = \frac{64}{3^3} T7=6427T_7 = \frac{64}{27}

    The 7th term is 6427\frac{64}{27}.

  3. Compare with the given options for question 5.

    The calculated 7th term is 6427\frac{64}{27}, which corresponds to option (C).
    The answer for question 5 is C\boxed{\text{C}}.

  4. Determine the sum to infinity for question 6.

    For a geometric series to have a sum to infinity, the absolute value of the common ratio ∣r∣|r| must be less than 1.
    The common ratio is r=23r = \frac{2}{\sqrt{3}}.
    To check if ∣r∣<1|r| < 1:

    r=23≈21.732≈1.1547r = \frac{2}{\sqrt{3}} \approx \frac{2}{1.732} \approx 1.1547

    Since r≈1.1547>1r \approx 1.1547 > 1, the condition ∣r∣<1|r| < 1 is not met. Therefore, the sum to infinity of this series does not exist.

  5. Compare with the given options for question 6.

    The conclusion is that the sum to infinity does not exist, which corresponds to option (D).
    The answer for question 6 is D\boxed{\text{D}}.

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