\ \
The series is . \ \
The sequence is an arithmetic sequence with first term . \ \
Find the sum . \ \
The sum of the first terms of an arithmetic sequence . \ \
. \ \
The sum of the series is .
![\"\"](\"/userfiles/image/steps_images/step1.JPG\")
\ \
\ \
![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=79f41d7c4a15d7c4d3676ee84284cfce.png\")
. \ \
![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=472102a2d1b9b55aff6e488491b6ab88.png\")
is an arithmetic sequence with first term ![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=87c0a06a78a1452b1187e0a3d6d44a11.png\")
. \ \
![\"\"](\"http://www.mathskey.com/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=22a5ca762df0a19294ed5a7d95cf1e09.png\")
. \ \
![\"\"](\"http://www.mathskey.com/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=9d9525296c7189f71cd1cbb29d5a4593.png\")
terms of an arithmetic sequence ![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=6707208ed5dfe6b04aaa9fe5f7ffbfe7.png\")
. \ \
![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=0c915f65d1f0dbe3b35beff4e763b5a7.png\")
\ \
![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=fbe015dcb7aab20472d7aabe0ed73fd8.png\")
\ \
![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=fa5077b0c7c1199c11bd3aa342ece5b6.png\")
. \ \
![\"\"](\"/userfiles/image/steps_images/solution.JPG\")
\ \
![\"\"](\"http://www.mathskey.com/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=fa5077b0c7c1199c11bd3aa342ece5b6.png\")
.