Find the sum of series : 7 + 77 + 777 ....... to n terms ?
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Answer:
the answer is 7/9[10(10n−1) / 9 −n] :)
Step-by-step explanation:
7 + 77 + 777 + ...till n terms
= 7 [1 + 11 + 111 + ... till n terms]
=7/9[9 + 99 + 999 + ... till n terms]
=7/9[(10 - 1) + (100 - 1) + (1000 - 1) + ... till n terms]
=7/9[(10 + 100 + 1000 + ... till n terms ) - (1 + 1 + 1+...till n terms)]
=7/9[10(10n−1) / 10−1 −n]
=7/9[10(10n−1) / 9 −n].
PLS MRK AS BRAINLIEST PLSSSS....... :)
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