Question

Find the sum of the finite geometric sequence

Answer 1

Answer:

45

Step-by-step explanation:

Use the geometric sum formula for in infinite sum. 20 terms of this basic formula is close enough The 20th term is 8.6 * 10^-10 which means this goes out to a number with 9 zeros after the decimal and before the 8.

Put another way, the tenth number of this series is the only one affected.

When you use a spreadsheet, it seems to know that the answer is 3/2 as the solution to the sum.

Solution.

Sum = a / (1 - r)

a = 1

r = 1/3

Sum = 1 / (1 - 1/3)

Sum = 1 // 2/3

sum =  3/2

Now you can worry about the 30.

30 * sum(1/3)^n = 30* 3/2 = 45

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