Given the sequence in the table below, determine the sigma notation of the sum for term 4 through term 15.


n an

1 4

2 −12

3 36

Verified Answer :

naǫ

It's a geometric sequence.

\(4,-12,36,... \\ \\ a_1=4 \\ r=\frac{a_2}{a_1}=\frac{-12}{4}=-3 \\ \\ a_n=a_1 \times r^{n-1} \\ a_n=4 \times (-3)^{n-1} \\ a_n=4 \times (-3)^{-1} \times (-3)^n \\ a_n=4 \times (-\frac{1}{3}) \times (-3)^n \\ a_n=-\frac{4}{3}(-3)^n\)

It's the sum for term 4 through term 15.

 \(\boxed{ \sum\limits_{n=4}^{15} (\frac{4}{3}(-3)^n)}\)

Answer:

The answer is in the picture bellow

Step-by-step explanation:

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