Question

in geometric progression
the sum of the series -2,6,-18 ...to 7 terms is

Answer 1

Given GP series,
-2,6, - 18..........................
Here, first term=a=-2
common ratio=r=6/-2=-3
We know that,
Sn={a1(1-r^n)}/(1-r)

S7={-2(1-(-3)^7)}/{1-(-3)}

S7={-2(1+2187)}/(1+3)

S7=-2(2188)/4

S7=-2(547)

S7=-1094


Hence sum of 7 terms of given GP is
-1094.

Answer 2

Answer:

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