An infinite geometric series has common ratio 1/8 and sum 80. What is the first term of the series?

Guest Jun 12, 2021

#1**+2 **

So it's given that r = 1/8 and S_{∞ }= 80

∵ We know that,

\({S}_{∞} = {a\over 1-r}\)

\(80={a\over 1-{1\over 8}}\)

\(80={8a\over 7}\)

⇒ \(a=70\)

amygdaleon305 Jun 12, 2021

#1**+2 **

Best Answer

So it's given that r = 1/8 and S_{∞ }= 80

∵ We know that,

\({S}_{∞} = {a\over 1-r}\)

\(80={a\over 1-{1\over 8}}\)

\(80={8a\over 7}\)

⇒ \(a=70\)

amygdaleon305 Jun 12, 2021