Q. Find the sum of the first 9 terms of the following geometric series.481−121+31−…The sum is □.
Identify terms and ratio: Identify the first term a and the common ratio r of the geometric series.The first term a is 481.To find the common ratio r, divide the second term by the first term: r=1/48−1/12=−4.
Use sum formula: Use the formula for the sum of the first n terms of a geometric series: Sn=(1−r)a(1−rn), where n is the number of terms.Here, n=9, a=481, and r=−4.
Calculate (−4)9: Plug the values into the formula: S_9 = \frac{\(1\)}{\(48\)}\left(\frac{\(1\) - (\(-4\))^\(9\)}{\(1\) - (\(-4\))}\right)\.
Substitute and simplify: Calculate \((-4)^9. Since 4 is even and the exponent 9 is odd, the result will be negative: (−4)9=−262144.
Add numbers in parentheses: Substitute the value into the sum formula: S9=481(1+41−(−262144)).
Substitute sum into formula: Simplify the expression: S9=481(1+262144)/5.
Multiply numerator: Add the numbers inside the parentheses: 1+262144=262145.
Divide by denominator: Substitute the sum into the formula: S9=481(262145)/5.
Final sum: Multiply the numerator: (481)×262145=5461.35416667 (rounded to 8 decimal places).
Final sum: Multiply the numerator: (481)×262145=5461.35416667 (rounded to 8 decimal places).Divide by the denominator: 5461.35416667/5=1092.27083333 (rounded to 8 decimal places).
Final sum: Multiply the numerator: (481)×262145=5461.35416667 (rounded to 8 decimal places).Divide by the denominator: 5461.35416667/5=1092.27083333 (rounded to 8 decimal places).The sum of the first 9 terms of the geometric series is approximately 1092.27083333.
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