Question

find the sum of two middle most terms of A. P
-4/3​

Answer 1

Answer:

Step-by-step explanation:

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11th

Maths

Sequences and Series

Arithmetic Progression

Find the sum of the two mid...

MATHS

Find the sum of the two middle most terms of the AP:  

3

1

​  

,  

3

2

​  

,1,…  

3

20

​  

 

EASY

ANSWER

a=  

3

1

​  

 

d=  

3

2

​  

−  

2

1

​  

=  

3

1

​  

 

T  

n

​  

=a+(n−1)d

3

20

​  

=  

3

1

​  

+(n−1)  

3

1

​  

 

20=1+(n−1)

20=1+n−1

20=n

Middle terms t=10,t=11

T  

10

​  

=  

3

1

​  

+(10−1)  

3

1

​  

 

T  

10

​  

=  

3

1

​  

+9(  

3

1

​  

)

T  

10

​  

=  

3

10

​  

 

T  

11

​  

=  

3

1

​  

+(11−1)  

3

1

​  

 

T  

11

​  

=  

3

1

​  

+10(  

3

1

​  

)

T  

11

​  

=  

3

11

​  

 

T  

10

​  

+T  

11

​  

=  

3

10

​  

+  

3

11

​  

=  

3

21

​  

=7

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