Question

Find the sum of the infinite series 1 + 2 + 4 + 8 +...if it exists.
1352
1353
1354
does not exist

Find s9 for the series 1+5+25+125
248, 321
284, 211
588, 451
488, 281

can someone explain how to do these??

Answer 1

1) does not esxist

Answer 2

2) first term is a= 1 and common ratio is r=5
s9 is given by a*(r^9 -1) /(r-1)

Answer 3

omg marry me :DDD

Answer 4

okay. I don't get the r^9 thing

Answer 5

what?

Answer 6

S9 means the sum of the first nine terms

Answer 7

r^9 means here 5^9 = 5*5*5.... 9 times...

Answer 8

OH!! oh okay I understand more thank you!!

Answer 9

welcome