SOLUTION: A G.P has 8 terms it first and last term are 0.3 and 38.4 calculate (a) the common ratio (b) the sum of the terms in the G.P

Algebra ->  Sequences-and-series -> SOLUTION: A G.P has 8 terms it first and last term are 0.3 and 38.4 calculate (a) the common ratio (b) the sum of the terms in the G.P       Log On


   

Question 1200760: A G.P has 8 terms it first and last term are 0.3 and 38.4 calculate
(a) the common ratio
(b) the sum of the terms in the G.P
Answer by Edwin McCravy(20056) About Me  (Show Source):
You can put this solution on YOUR website!

0.3, 0.3r, 0.3r2, 0.3r3, 0.3r4, 0.3r5, 0.3r6, 0.3r7 = 38.4

0.3r7 = 38.4
 Divide both sides by 0.3
r7 = 128
r=root%287%2C128%29=2

S%5Bn%5D=%28r%2Aa%5Bn%5D-a%5B1%5D%29%2F%28r%5E%22%22-1%29

S%5B8%5D=%282%2A38.4-0.3%29%2F%282-1%29

S%5B8%5D=%2876.8-0.3%29%2F%281%29

S%5B8%5D=76.8-0.3

S%5B8%5D=76.5

Edwin