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A geometric series has a second term of −43 and a fifth term of 3281 . Find the sum of the first 10 terms.

User MHOOS
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Final answer:

To find the sum of the first 10 terms of a geometric series, use the given terms to find the common ratio and the first term, then use the formula for the sum of a geometric series. After calculation, the sum comes up to 349525.

Step-by-step explanation:

To find the sum of the first 10 terms of a geometric series, we need to find the common ratio and the first term. Let's denote the first term as a and the common ratio as r. We are given that the second term is -43 and the fifth term is 3281.

We can use the formula for the nth term of a geometric series to set up two equations:

a * r = -43 (equation 1)

a * r^4 = 3281 (equation 2)

By dividing equation 2 by equation 1, we can solve for r:

r^3 = -3281/-43

r^3 = 76

r = 4

Now, we can substitute the value of r into equation 1 to find the first term:

a * 4 = -43

a = -43/4

Finally, we can use the formula for the sum of the first n terms of a geometric series:

Sum = a * (1 - r^n) / (1 - r)

Plugging in the values given, we get:

Sum = (-43/4) * (1 - 4^10) / (1 - 4)

Sum = -43 * (1 - 1048576) / -3

Sum = 349525

User GlyphGryph
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