find the sum of n terms of the series 7+77+777+................upto n terms
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(7/9)[10(10n-1)/(9)-n]
barsha9:
sry wrong answer
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7 + 77 + 777 +.........
7[1 + 11 + 111 + ..........]
7/9[9 + 99 + 999 +.......]
7/9[(10-1) + (100-1) + (1000-1).......]
7/9[(10 + 100 + 1000.....) - (1+1+1........)]
7/9[ {10(10^n - 1)/(10-1)} - n]
7/9[10(10^n - 1)/9 - n]
7/9[10(10^n - 1) - 9n]/9
7/81[ 10(10^n - 1) - 9n]
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o_O
7[1 + 11 + 111 + ..........]
7/9[9 + 99 + 999 +.......]
7/9[(10-1) + (100-1) + (1000-1).......]
7/9[(10 + 100 + 1000.....) - (1+1+1........)]
7/9[ {10(10^n - 1)/(10-1)} - n]
7/9[10(10^n - 1)/9 - n]
7/9[10(10^n - 1) - 9n]/9
7/81[ 10(10^n - 1) - 9n]
♡♥♡♥♡♥
o_O
oo
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ese hi
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oo
u know what
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for head boy and head girl
thats it now ur turn
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