Question

Find the arithmetic mean of 7, 77, 777, ... upto pth term. 7. Let the arithmetic mean of xj. I, ... Ig (x, 5 msasa​

Answer 1

Answer:

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Answer 2

Step-by-step explanation:

7,77,777,777to n terms.

Sn=7+77+777+7777+to n terms

introducing 9

=

9

7

[9+99+999+ to n terms]

=

9

7

[(10−1)+(100−1)+(1000−1) + to n term]

=

9

7

[10+100+1000 + n terms - (1+1+1+1+ n terms)

=

9

7

[10+100+1000+n terms -n ]

Here a=10,r=10

=

9

7

[

9

10(10

n

−1)

−n]

=

81

70

(10

n

−1)−n