Question

7. find the sum to n terms of the A.P....,whose k term is 5k+1​

Answer 1

Answer:

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Answer 2

Step-by-step explanation:

give that

kth term =5k+1

ak =5k+1

putting k = 1

a1=5×1+1

= 6

similarly,

putting k =2

a2 = 5×2 +1

=11

putting k =3

=16

thus our A.P becomes 6, 11, 16....

here

first term a=6

d=11-6 = 5

we need to find the sum of n term i.e Sn

sn = n/2 (2a+(n-1) d)

putting values a =6 d = 5

=n/2 (12+ (n-1)5)

=n/2 (5N+7)

hence the sum of n term of the A.P is n/2 (5n+7)

hope it helpss !! :D