1.

An infinite G.P has first term x and sum 5 then x belongs to ?A. `xlt-10`B. `-10ltxlt0`C. `0ltxlt10`D. `xgt0`

Answer» Correct Answer - C
Let r be the common ratio of the G.P. Then, `-1ltrlt1`.
Now,
Sum=5
`rArr" "(x)/(1-r)=5`
`rArr" "1-r=(x)/(5)`
`rArr" "r=1-(x)/(5)`
`rArr" "-1lt1-(x)/(5)lt" "[because-1ltrlt1]`
`rArr" "-2lt-(x)/(5)lt0rArr2gt(x)/(5)gt0rArr10gtxgt0rArrltxlt10`


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