Naicarlz1viz
Answered

geometric progression! HELP

 a=1st term, n=no. of terms, r=common ration, L= last term 


````1. r = -4, n = 6, S = -1.819; find a 

``````2. a = 8, r = 3/2, S = 2059/8; find n 

````````3. a = 3, r = 2/5, S = -609/125; find L

Sagot :

Elijahlicodiniviz
1.the formula by getting the first term is S=a(r^n-1) /r-1 so direct substitution . the answer is -107/48200
2.this is direct substitution again . so n=3.215
3.direct substitution n=3.31 and the formula by getting the last term isL=ar^n-1 so the last term is 0.35