If the sum of an infinite G.P. be 9 and the s | vedclass

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Question

(d) Infinite series is $a,\;ar,\;a{r^2}........\infty $

Sum $S = \frac{a}{{1 - r}} = 9 $

$\Rightarrow a = 9(1 - r)$ &hellip;..$(i)$

and $a +

Vedclass · Accepted Answer

$2/3$

Vedclass · Answer

(d) Infinite series is $a,\;ar,\;a{r^2}........\infty $

Sum $S = \frac{a}{{1 - r}} = 9 $

$\Rightarrow a = 9(1 - r)$ &hellip;..$(i)$

and $a + ar = 5$

$ \Rightarrow a(1 + r) = 5 $

$\Rightarrow 9(1 - r)(1 + r) = 5$ [By equation $(i)$]

$1 - r^2 = \frac{{5}}{{9}}$

$\Rightarrow r = \pm \frac{{2}}{{3}}$

If the sum of an infinite $G.P.$ be $9$ and the sum of first two terms be $5$, then the common ratio is

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