In an ap the sum of its n term is 6n - n^2 find its 25term
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Given,
Sum of n terms=6n-n²
Sum of 1 term =6(1)-1²=5 ...eq(1)
Sum of 2 terms =6(2)-2²=8
Sum of 3 terms =6(3)-3²=9
Now First term =5
Second term =8-5=3
Third term =9-8=1
Common difference =3-5=1-3=-2
We know nth term = a1 + (n – 1) d.
Now ,25 th term = 5+(25-1)2=5+(24)×-2=5-48=-43.
Hence ,The 25 term is -43 .
Sum of n terms=6n-n²
Sum of 1 term =6(1)-1²=5 ...eq(1)
Sum of 2 terms =6(2)-2²=8
Sum of 3 terms =6(3)-3²=9
Now First term =5
Second term =8-5=3
Third term =9-8=1
Common difference =3-5=1-3=-2
We know nth term = a1 + (n – 1) d.
Now ,25 th term = 5+(25-1)2=5+(24)×-2=5-48=-43.
Hence ,The 25 term is -43 .
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