In an A.P,the sum of its first n term is 6n-n².Find its 25th term
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Answered by
272
hi friend,
given In an A.P,the sum of its first n term is 6n-n².sum of 1st term is
s1=6(1)-(1)²=6-1=5=a(first term)
sum of two terms s2=6(2)-(2)²=12-4=8
a1+a2=8
5+a2=8
a2=3
so the common difference is a2-a1=-2
so 25th term is a+(24)d
5-48
=-43
I hope this will help u ;)
given In an A.P,the sum of its first n term is 6n-n².sum of 1st term is
s1=6(1)-(1)²=6-1=5=a(first term)
sum of two terms s2=6(2)-(2)²=12-4=8
a1+a2=8
5+a2=8
a2=3
so the common difference is a2-a1=-2
so 25th term is a+(24)d
5-48
=-43
I hope this will help u ;)
Answered by
58
Here's the solution.
Hope it helps.
Hope it helps.
Attachments:
This is an entirely different approach you might not have seen before
seen it
In it, you try to adjust the formula into standard form. There you get an important result, which I have put in the box as equation 1.
Oh, good that you know about it
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