if the 21st term of an A.P. is 25, find the sum of it's first 41 terms.
Answers
Answered by
443
25=a+(20)d
a= 25-20d
s41=(41/2)2(25-20d)+(40d)
=(41/2)50-40d+40d
=50(41/2)
=1025
please mark my answer as brainliest if this helped you
a= 25-20d
s41=(41/2)2(25-20d)+(40d)
=(41/2)50-40d+40d
=50(41/2)
=1025
please mark my answer as brainliest if this helped you
Ayushasutkar:
plz check it
anyway
the question
( 1 + tan²∅) ( 1 - sin∅) ( 1 + sin∅)
plz simplify
okay
what is formula of sn
Answered by
128
Answer:
A.T.Q
a²¹ =a+20d
25=a+20d
a =25-20d
Then,
S⁴¹=41/2[2a +40d]
=41/2[2(25-20d)+40d]
=41/2[2(25-20d)+2(20d)]
=41/2×2(25-20d+20d)
=41(25)
=1025. Ans
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