Question

if the 21st term of an A.P. is 25, find the sum of it's first 41 terms.

Answer 1

good afternoon , friend your ans is here:-


here , a21 = 25


=) a + (n-1) d = 25


=) a + (21 - 1 ) d =25


=) a+ 20 d = 25



now sum of the first 41 terms :-


= 41/2 {2a + (n-1)d }


= 41/2 { 2a + ( 41-1) d}


= 41/2 { 2a + 40 d } .



☺ hey friend I hope this ans would help you.



■{♡♡♡ THANK YOU ♡♡♡}.■

Answer 2

The solution is in the following image..
Hope it helps..
Answer is 1025..

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