Find the sum:  7+77+777+.....upto n terms.

Hi Heenal!
Here is the answer to your question.
 
7 + 77 + 777 + … to n terms
Let Sn = 7 + 77 + 777 + … to n terms
 
Hope you got the answer.
 
Cheers!

  • 84

please explain more eaisly ....!!

can't understand....!!

:(

sn = n/2 [2a+(n-1)d)]

i can't understand what u have done..!!!

:(

:(

  • 2

Sir I got the problem till 4th step where you got

7/9[10(10n-1)/10-9 -n but, in the dinominator 10-9 is 1 and you have taken 9 in the next step and its a geometric progression ie. sn= a [(rn-1)/(r-1) where r>1... please give an explanation if I am wrong.....

  • 10
What are you looking for?