Question 3o show all workFind the sum of2i 3(a 1+an

asked Sep 7, 2017 205k views

1 vote

8.1k points

Please log in or register to add a comment.

3 votes

$n=8\\ a_1=2\cdot3+3=9\\ a_n=a_8=2\cdot10+3=23\\\\ \displaystyle \sum\limits_(i=3)^(10)2i+3=S_8=(8)/(2)\cdot(9+23)=4\cdot32=128$

Somnium answered Sep 13, 2017