1 Answer
Solution :-
5 + 55 + 555 + … to n terms.
Let us take 5 as a common term so we get,
5 [1 + 11 + 111 + … n terms]
Now multiply and divide by 9 we get,
\( \dfrac{5}{9}\) [9 + 99 + 999 + … n terms]
\( \dfrac{5}{9}\)[(10 – 1) + (102 – 1) + (103 – 1) + … n terms]
\( \dfrac{5}{9}\)[(10 + 102 + 103 + … n terms) – n]
So the G.P is
\( \dfrac{5}{9}\)[(10 + 102 + 103 + … n terms) – n]
Where, a = 10, r = \( \dfrac{10^2}{10}\) = 10, n = n
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