rockdrummer5206
New member
Alright so i'm supposed to write the expression for the nth term of the geometric sequence and find the sum of the first 20 terms of the sequence...
for problem 65 is tells me that a (subscript)1 = 16 and a (subscript)2 = -8
I then figured that r is = to -2 so my expression is Sn=16(-1/2)^20-1?
how do I find the sum of the first 20 terms? my book tells me that the answer is 10.67 but I can not seem to get that.
for problem 65 is tells me that a (subscript)1 = 16 and a (subscript)2 = -8
I then figured that r is = to -2 so my expression is Sn=16(-1/2)^20-1?
how do I find the sum of the first 20 terms? my book tells me that the answer is 10.67 but I can not seem to get that.