use the sum of the first 10 terms to approximate the sum of the series. (round your answer to five decimal…

use the sum of the first 10 terms to approximate the sum of the series. (round your answer to five decimal places.)\n sum _ { n = 1 } ^ { infty } 3 ^ { - n } cos ^ { 2 } ( n ) \n0.16012\nestimate the error. (round your answer to eight decimal places.)\n r _ { 10 } leq int _ { 10 } ^ { infty } \frac { 1 } { 3 ^ { x } } d x = \n
Answer
Explanation:
Step1: Integrate the function
Recall the integral formula (\int a^{x}dx=\frac{a^{x}}{\ln a}+C) ((a > 0,a\neq1)). For the integral (\int\frac{1}{3^{x}}dx=\int3^{-x}dx), let (u=-x), then (du=-dx). So (\int3^{-x}dx=-\frac{3^{-x}}{\ln 3}+C).
Step2: Evaluate the definite - integral
Using the fundamental theorem of calculus (\int_{10}^{\infty}\frac{1}{3^{x}}dx=\lim_{t\rightarrow\infty}\int_{10}^{t}3^{-x}dx). [ \begin{align*} \lim_{t\rightarrow\infty}\int_{10}^{t}3^{-x}dx&=\lim_{t\rightarrow\infty}\left[-\frac{3^{-x}}{\ln 3}\right]{10}^{t}\ &=\lim{t\rightarrow\infty}\left(-\frac{3^{-t}}{\ln 3}+\frac{3^{-10}}{\ln 3}\right) \end{align*} ] Since (\lim_{t\rightarrow\infty}3^{-t}=\lim_{t\rightarrow\infty}\frac{1}{3^{t}} = 0).
Answer:
(\frac{1}{3^{10}\ln 3}\approx\frac{1}{59049\times1.098612289}\approx0.00001543)