Question

1)Find the sum of n terms of the sequence 11,102,1003,10004……….?

Answer 1

Answer:

ANSWER

11,103,1005…

(10+1),(1  

2

+3),(10  

3

+5)…

[10+10  

2

+10  

3

…]+[1+3+5+7…]

G.P.

a=10,

r=10.     +      A.P.

b=1,

d=2.

S  

n

​  

=S  

1

​  

+S  

2

​  

 

S  

n

​  

=  

r−1

a(r  

n

−1)

​  

+  

2

n

​  

[2b+(n−1)d]

S  

n

​  

=  

9

10(10  

n

−1)

​  

+  

2

n

​  

[2b+(n−1)2]

S  

n

​  

=  

9

10

​  

(10  

n

−1)+n[1+n−1]

S  

n

​  

=  

9

10

​  

(10  

n

−1)+n  

2

Step-by-step explanation:

Answer 2

Step-by-step explanation:

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refer to the attachment