Question

anser plz i will help him​

Answer 1

Answer:

(

Step-by-step explanation:

(a) a = 1 ,d = 2 , sum of 'n' terms =(n/2) (2a+(n-1)d)

n =5

sum of 5 terms = (5/2) (2+(4×2)) = 5×10/2 =25

(b) sum of 'n' terms = (n/2) (2+(n-1)2)

= n (1+n-1)= n^2

(c) sum of n terms =1/n +3/n + 5/n ...........

=(1/n)( 1+3+5+7.....)

from the part (b),

sum = ( 1/n) (n^2)

= n

(d) part d is similar to part c so we can take 'n' = 2020

sum of such 2020 terms = n = 2020