How do you find the sum of the arithmetic sequence given a1=3, d=-4, n=8?
1 Answer
Sep 14, 2016
Explanation:
The sum to n terms of an arithmetic sequence is.
#color(orange)"Reminder"#
#color(red)(bar(ul(|color(white)(a/a)color(black)(S_n=n/2[2a+(n-1)d])color(white)(a/a)|)))#
where a is the first term, d the common difference and n, the terms being summed.here a = 3 , d =- 4 and n = 8
#rArrS_8=8/2[(2xx3)+(7xx-4)]#
#=4(6-28)=-88#
