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Question : 143 of 150
Marks:
+1,
-0
Solution:
Comparing the given series with
1+nx+‌x2+.... we get
nx=‌ and
‌x2=‌ ∴‌‌‌=2⇒n−1=2n ⇒‌‌n=−‌ and
‌⋅x=‌⇒x=−‌ ∴ Sumof series
=(‌)−1∕3=(‌)−1∕3=(‌)1∕3
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