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Find the sum of n terms of the sequence 5+55+555....  
Asked by gsitabhanu24 | 01 Feb, 2019, 03:46: PM
answered-by-expert Expert Answer
Sum = 5 + 55 + 555 + …. n terms.
= 5/9 [9 + 99 + 999 + …. n terms]
= 5/9 [(10 – 1) + (100 – 1) + (1000 – 1) + … n terms]
= 5/9 [10 + 100 + 1000 ….. – (1 + 1 + … 1)]
= 5/9 [10(10n – 1)/(10 – 1) + (1 + 1 + … n times)]
= 50/81(10n – 1) – 5n/9
Answered by Science Mate | 01 Feb, 2019, 04:31: PM

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