Question

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Find the sum of the first 5 terms of the geometric series. 8 – 16 + 32 – ... 87
86
88
89

Answer 1

Answer: c) 88

Explanation:

8, -16, 32, ...

We can see that each previous term is multiplied by -2

so the next two terms will be 32(-2) = -64 and -64(-2) = 128

So the first 5 terms of the sequence is: 8, -16, 32, -64, 128

Add the positive numbers and the negative numbers, then find their sum.

8 + 32 + 128 = 168

-16 + (-64) = -80

Sum = 88