How do you find the sum of the first 10 terms of #1+9+81+729+...#?

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Answer 1 · 2016-07-26T09:29:21

#435,848,050#

First we need to know whether it is an AP or GP.??

The difference changes, so it is not an AP. However #81/9 =9/1 = 9#
So it is a GP.

#a = 1 and r = 9#

Use the formula for the sum of #n# terms:

#S_n = (a(r^n - 1))/(r-1)#

For n = 10.

#S_n =(1(9^10 -1))/(9-1)#

This is the huge answer of #435,848,050#