Question Number 66439 by Rio Michael last updated on 15/Aug/19
$${for}\:{a}\:{geometric}\:{series}. \\ $$$${can}\:{the}\:{sun}\:{to}\:{infinty}\:{use}\:{the}\:{two}\:{formulas} \\ $$$${S}_{\infty} =\:\frac{{a}}{\mathrm{1}−{r}}\:\:\mid{r}\mid\:\:<\mathrm{1}\:\:{and}\:{S}_{\infty} \:=\:\frac{{a}}{{r}−\mathrm{1}}\:\mid{r}\mid\:>\:\mathrm{1}\:??\:{please}\:{i}\:{am}\:{getting}\:{confused}\:{on}\:{this}. \\ $$
Commented by JDamian last updated on 15/Aug/19
$${The}\:{sum}\:{when}\:\:{n}\rightarrow\infty\:\:{and}\:\:{r}>\mathrm{1}\:\:{is}\:\pm\infty \\ $$
Commented by Rio Michael last updated on 15/Aug/19
$${so}\:{it}\:{can}\:{be}\:{used}?\:{i}\:{mean}\:{the}\:{second}\:{formula} \\ $$
Commented by Kunal12588 last updated on 15/Aug/19
$${when}\:{the}\:{series}\:{is}\:{converging}\:{those}\:{formulas} \\ $$$${can}\:{be}\:{used} \\ $$
Commented by Rio Michael last updated on 15/Aug/19
$${thanks} \\ $$