in an ap the sum of its first n terms is 6n-n^2.Find its 25th term
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hey mate
here is your answer
when n=1
s=n/2(2a+(n-1)d)
6*1-1²=1/2(2a+(1-1)d)
5=1/2(2a)
=5=a
when n=2
6*2-2²=2/2(2*5+(2-1)d)
8=(10+d)
d=-2
therefore
25th term=5+24*-2
=-48+5
=-43
here is your answer
when n=1
s=n/2(2a+(n-1)d)
6*1-1²=1/2(2a+(1-1)d)
5=1/2(2a)
=5=a
when n=2
6*2-2²=2/2(2*5+(2-1)d)
8=(10+d)
d=-2
therefore
25th term=5+24*-2
=-48+5
=-43
usra4:
the ans is -43
wait
let me check
hey now check
sorry for the mistake
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