![\bf -15~~,~~\stackrel{-15+4}{-11}~~,~~\stackrel{-11+4}{-7}~~,~~\stackrel{-7+4}{-3}~~~~,...\qquad \qquad \boxed{d=4} \\\\[-0.35em] ~\dotfill\\\\ n^{th}\textit{ term of an arithmetic sequence} \\\\ a_n=a_1+(n-1)d\qquad \begin{cases} n=n^{th}\ term\\ a_1=\textit{first term's value}\\ d=\textit{common difference}\\[-0.5em] \hrulefill\\ d=4\\ a_1=-15\\ n=27 \end{cases} \\\\\\ a_{27}=-15+(27-1)4\implies a_{27}=-15+(26)4 \\\\\\ a_{27}=-15+104 \implies a_{27}=89](/tpl/images/0454/4264/97635.png)
![\bf \rule{34em}{0.25pt}\\\\ \textit{ sum of a finite arithmetic sequence} \\\\ S_n=\cfrac{n(a_1+a_n)}{2}\qquad \begin{cases} n=n^{th}\ term\\ a_1=\textit{first term's value}\\[-0.5em] \hrulefill\\ n=27\\ a_1=-15\\ a_{27}=89 \end{cases} \\\\\\ S_{27}=\cfrac{27(a_1+a_{27})}{2}\implies S_{27}=\cfrac{27(-15+89)}{2}\implies S_{27}=\cfrac{27(74)}{2} \\\\[-0.35em] \rule{34em}{0.25pt}\\\\ ~\hfill S_{27}=999~\hfill](/tpl/images/0454/4264/2a5fd.png)
What is the sum of the first 27 terms of the arithmetic sequence?
-15,-11,-7,-...
Mathematics, 14.01.2020 14:31 snikergrace
What is the sum of the first 27 terms of the arithmetic sequence?
-15,-11,-7,-
Answers: 1
Another question on Mathematics
Mathematics, 21.06.2019 18:30
Suppose your school costs for this term were $4900 and financial aid covered 3/4 of that amount. how much did financial aid cover? and how much do you still have to pay?
Answers: 1
Mathematics, 21.06.2019 19:40
Molly shared a spool of ribbon with 12 people. each person received 3 feet of ribbon. which equation can she use to find r, the number of feet of ribbon that her spool originally had?
Answers: 1
Mathematics, 21.06.2019 22:40
Which of the following functions corresponds to the above sinusoid? a. 10 cos πx - 5 b. -5 sin x - 5 c. -10 cos πx/2 - 0.5 d. 10 sin πx - 5
Answers: 1
Mathematics, 22.06.2019 00:00
If (x + 8) is a factor of f(x), which of the following must be true? both x = –8 and x = 8 are roots of f(x). neither x = –8 nor x = 8 is a root of f(x). f(–8) = 0 f(8) = 0
Answers: 3
You know the right answer?
Questions
Mathematics, 27.10.2020 15:50
Mathematics, 27.10.2020 15:50
Mathematics, 27.10.2020 15:50
Mathematics, 27.10.2020 15:50
Mathematics, 27.10.2020 15:50
English, 27.10.2020 15:50
Chemistry, 27.10.2020 15:50
Mathematics, 27.10.2020 15:50
Computers and Technology, 27.10.2020 15:50
Mathematics, 27.10.2020 15:50
Mathematics, 27.10.2020 15:50
English, 27.10.2020 15:50
English, 27.10.2020 15:50
