+116 I can't figure out this one
Find the Indicated sum
\(\sum_{i=1}^{Infinity} (-\frac{2}{5})^i-1\)
the exponet is soppose to be i-1
Thank you for your help!! 
+118677 Hi BlueFire28, it is nice to meet you :)
I can't figure out this one
Find the Indicated sum
the exponet is soppose to be i-1
Thank you for your help!!
\(\sum_{i=1}^\infty\;\left(\frac{-2}{5}\right)^{i-1}\\~\\ 1+\frac{-2}{5}+\frac{4}{25}+ \ldots\\ \mbox{This is the sum of a GP and it has a limit since r=-2/5 and |r|<1}\\ S_{\infty}=\frac{a}{1-r}=\frac{1}{1-\;-0.4}=\frac{1}{1.4}=\frac{5}{7}\\ so\\ \sum_{i=1}^\infty\;\left(\frac{-2}{5}\right)^{i-1}=\frac{5}{7}\\~\\ \)
+118677 Hi BlueFire28, it is nice to meet you :)
I can't figure out this one
Find the Indicated sum
the exponet is soppose to be i-1
Thank you for your help!!
\(\sum_{i=1}^\infty\;\left(\frac{-2}{5}\right)^{i-1}\\~\\ 1+\frac{-2}{5}+\frac{4}{25}+ \ldots\\ \mbox{This is the sum of a GP and it has a limit since r=-2/5 and |r|<1}\\ S_{\infty}=\frac{a}{1-r}=\frac{1}{1-\;-0.4}=\frac{1}{1.4}=\frac{5}{7}\\ so\\ \sum_{i=1}^\infty\;\left(\frac{-2}{5}\right)^{i-1}=\frac{5}{7}\\~\\ \)
