The sum of the geometric sequence (1 Viewer)

[ClockworkSoldier]

I'm not a maths mind, but my friend needs this answered with workings.

S17 = 64 ( 1/2^17 - 1) / 1/2 - 1

Thanks in advance!

 

[Timothy.Siu]

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[speter]

its wrong his using the wrong Sn the result from what you gave me is going to be negative. Your friend used Sn= a(r^n-1)/r-1 his meant to use Sn=a(1-r^n)/1-r

 

[ClockworkSoldier]

Thanks lol.

What would the answer for that be?

 

[uart]

its wrong his using the wrong Sn the result from what you gave me is going to be negative. Your friend used Sn= a(r^n-1)/r-1 his meant to use Sn=a(1-r^n)/1-r

Nonsense, those two forms are exactly the same thing. Negative divided by negative is positive so it was fine as it was.

AusBluesMan, just make sure that you use brackets on that denominator, Sn=a(r^n-1)/(r-1), when using an ordinary divide symbol (as opposed to a "fraction bar" which has implied grouping).