if 21st term of an A.P is 25 find the sum of its first 41 term
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let the A.P be a,a+d,a+2d.........
given that a+20d =25
so a=25-20d.
sum of 41 terms will be 41\2*[2a+(41-1)d]
put value of a here
we get 41\2[50-40d+40d]
sum=41*25=1025
hope this answer will help u please follow me if u like my answer.
given that a+20d =25
so a=25-20d.
sum of 41 terms will be 41\2*[2a+(41-1)d]
put value of a here
we get 41\2[50-40d+40d]
sum=41*25=1025
hope this answer will help u please follow me if u like my answer.
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