Question

In an AP if a=20,d=40.4,n=10,find sn ??

Answer 1

Sn = n\2 [ 2a + ( n - 1 ) d ]

     = 10\2 [ 2(20) + ( 10 - 1 ) 40.4 ]

     = 5 [ 40 + 363.6 ]

     = 5 [ 403.6 ]

Therefore,

                  Sn = 2018

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Answer 2

Step-by-step explanation:

sn= n/2 {2a+(n-1)d}. 10/2 {2(20)+(10-1)40.4}. 5{40+363.6}. 5{403.6}. sn=2018.0