the first term of an Ap is 5 the last term is 45 and the sum of all terms is 400 find the number of the terms and the common difference of the Ap
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imkunal2u:
in your answer common difference is wrong please correct it
you have written 8/5 it should be 8/3
oh
sorry
it's okay... correct it
Answered by
6
Given that-
A1=5
An=45
Sn=400
we have to find-
n=?
d=?
An=A1+(n-1)d
45=5+(n-1)d
45-5=(n-1)d
Therefore, (n-1)d=40.........(i)
Sn=n/2[2A+(n-1)d]
400=n/2[2×5+40]. (from(i))
400×2=n(10+40)
800=n×50
n=800/50
n=16
put n=16 in (i),
(n-1)d=40
(16-1)d=40
15d=40
d=40/15
d=8/3
hope it will help you.....
A1=5
An=45
Sn=400
we have to find-
n=?
d=?
An=A1+(n-1)d
45=5+(n-1)d
45-5=(n-1)d
Therefore, (n-1)d=40.........(i)
Sn=n/2[2A+(n-1)d]
400=n/2[2×5+40]. (from(i))
400×2=n(10+40)
800=n×50
n=800/50
n=16
put n=16 in (i),
(n-1)d=40
(16-1)d=40
15d=40
d=40/15
d=8/3
hope it will help you.....
please mark it as brainliest
plzzx
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