Question

Please check this answer, not sure if I did this correctly.

What is the sum of the geometric sequence 8, -16, 32 . if there are 15 terms?

sum = 983100

Answer 1

Anyone one know if this is correct?

Answer 2

@nphuongsun93

Could you take a look at this when you have a chance?

Answer 3

you forgot the changing sign
i got 87384

Answer 4

formula for geometric sequence when ratio is < 1 = a(1-r^n) / (1-r)

8(1-(-2)^15)/(1+2)

i got 87384 too

Answer 5

I see it now, thanks