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Write the sum \(\displaystyle 46+54+62 \ldots +302+310\) in sigma notation and then find the sum.
The common difference is given by \(\displaystyle a_2-a_1=54-(46)=8\). Using the first term gives the sequene \(\displaystyle a_n= 46+(n-1)(8)\). Setting the general term equal to the last term and solving for \(\displaystyle n\) gives \(\displaystyle 46+(n-1)(8)=310 \implies n = 34 \). Writing in sigma notation gives \(\displaystyle \displaystyle \sum_{n=1}^{34} \left(8 n + 38\right)\). Using the formula for a finite arithmetic sum gives \(\displaystyle \frac{ 34(46+310) }{2}=6052\).
\begin{question}Write the sum $46+54+62 \ldots +302+310$ in sigma notation and then find the sum. \soln{9cm}{The common difference is given by $a_2-a_1=54-(46)=8$. Using the first term gives the sequene $a_n= 46+(n-1)(8)$. Setting the general term equal to the last term and solving for $n$ gives $46+(n-1)(8)=310 \implies n = 34 $. Writing in sigma notation gives $\displaystyle \sum_{n=1}^{34} \left(8 n + 38\right)$. Using the formula for a finite arithmetic sum gives $\frac{ 34(46+310) }{2}=6052$. } \end{question}
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<p> <p>Write the sum <img class="equation_image" title=" \displaystyle 46+54+62 \ldots +302+310 " src="/equation_images/%20%5Cdisplaystyle%2046%2B54%2B62%20%5Cldots%20%2B302%2B310%20" alt="LaTeX: \displaystyle 46+54+62 \ldots +302+310 " data-equation-content=" \displaystyle 46+54+62 \ldots +302+310 " /> in sigma notation and then find the sum.</p> </p>
<p> <p>The common difference is given by <img class="equation_image" title=" \displaystyle a_2-a_1=54-(46)=8 " src="/equation_images/%20%5Cdisplaystyle%20a_2-a_1%3D54-%2846%29%3D8%20" alt="LaTeX: \displaystyle a_2-a_1=54-(46)=8 " data-equation-content=" \displaystyle a_2-a_1=54-(46)=8 " /> . Using the first term gives the sequene <img class="equation_image" title=" \displaystyle a_n= 46+(n-1)(8) " src="/equation_images/%20%5Cdisplaystyle%20a_n%3D%2046%2B%28n-1%29%288%29%20" alt="LaTeX: \displaystyle a_n= 46+(n-1)(8) " data-equation-content=" \displaystyle a_n= 46+(n-1)(8) " /> . Setting the general term equal to the last term and solving for <img class="equation_image" title=" \displaystyle n " src="/equation_images/%20%5Cdisplaystyle%20n%20" alt="LaTeX: \displaystyle n " data-equation-content=" \displaystyle n " /> gives <img class="equation_image" title=" \displaystyle 46+(n-1)(8)=310 \implies n = 34 " src="/equation_images/%20%5Cdisplaystyle%2046%2B%28n-1%29%288%29%3D310%20%5Cimplies%20n%20%3D%2034%20%20" alt="LaTeX: \displaystyle 46+(n-1)(8)=310 \implies n = 34 " data-equation-content=" \displaystyle 46+(n-1)(8)=310 \implies n = 34 " /> . Writing in sigma notation gives <img class="equation_image" title=" \displaystyle \displaystyle \sum_{n=1}^{34} \left(8 n + 38\right) " src="/equation_images/%20%5Cdisplaystyle%20%5Cdisplaystyle%20%5Csum_%7Bn%3D1%7D%5E%7B34%7D%20%5Cleft%288%20n%20%2B%2038%5Cright%29%20" alt="LaTeX: \displaystyle \displaystyle \sum_{n=1}^{34} \left(8 n + 38\right) " data-equation-content=" \displaystyle \displaystyle \sum_{n=1}^{34} \left(8 n + 38\right) " /> . Using the formula for a finite arithmetic sum gives <img class="equation_image" title=" \displaystyle \frac{ 34(46+310) }{2}=6052 " src="/equation_images/%20%5Cdisplaystyle%20%5Cfrac%7B%2034%2846%2B310%29%20%7D%7B2%7D%3D6052%20" alt="LaTeX: \displaystyle \frac{ 34(46+310) }{2}=6052 " data-equation-content=" \displaystyle \frac{ 34(46+310) }{2}=6052 " /> . </p> </p>