Advertisements
Advertisements
Question
Q 10.3
Sum
Solution
Required sum = 2 + 22 + 222 +..........upto n terms
= 2(1 + 11 + 111 +..........upto n terms
=`2/9`(9 + 99 + 999 +..........upto n terms
=`2/9`[(10 - 1) + (100 - 1) +(1000 - 1) +..........upto n terms]
=`2/9`[(10 + 102 + 103 +..........upto n terms) - (1 + 1 + 1 +..........upto n terms)]
`=2/9[(10(10^n-1))/(10-1)-"n"]`
`=2/9[10/9(10^n-1)-"n"]`
shaalaa.com
Geometric Progression - Finding Sum of Their First ‘N’ Terms
Is there an error in this question or solution?
