Find the sum of the series, 7+77+777+......... to n terms
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the formula is tn=a+(n-1)d
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5
Write it as 7/9(9+99+999+............99999..n)
Then write
7/9(10-1+100-1+1000-1+.......10^n-1)
=7/9(n+10+100+1000+....)
Then use GP formula 10(10^n-1)/9
And solve further,u get
7/81(9n+10^n-1)
Please mark as brainliest
Then write
7/9(10-1+100-1+1000-1+.......10^n-1)
=7/9(n+10+100+1000+....)
Then use GP formula 10(10^n-1)/9
And solve further,u get
7/81(9n+10^n-1)
Please mark as brainliest
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