imrealconfused
imrealconfused imrealconfused
  • 18-06-2016
  • Mathematics
contestada

What is the sum of the first nine terms of the geometric series where a1 = 7 and r = −3?

Respuesta :

hartnn
hartnn hartnn
  • 18-06-2016
Sum of terms of a geometric series
Sn = a1 (r^n-1)/(r-1)
a1 = 1st term = 7
n = number of terms = 9
r = common ratio  = -3

Sn = 7 ((-3)^8-1)/(-3-1) = -11480
Hence the sum is -11480.
Answer Link

Otras preguntas

8 - 3 ( p - 4 ) = 2p
why is mercury usually hard to see without a telescope?
a croquet ball weighs 460 grams. together a golf ball and a croquet ball weigh the same as 11 golf balls.how much does 1 golf ball weigh?
a croquet ball weighs 460 grams. together a golf ball and a croquet ball weigh the same as 11 golf balls.how much does 1 golf ball weigh?
8 - 3 ( p - 4 ) = 2p
after 1081 ,what was the byzantine being weakened by?
why was the constantinople so important?
A 2-inch-wide frame is to be built around theregular decagonal window shown. At what angles a and bshould the corners of each piece be cut?
what is 2t^3+8t^2-24t in factor form
after 1081 ,what was the byzantine being weakened by?