In an AP 8.11,14..... Find Sn-Sn-1
Answers
Answered by
12
Sn - Sn-1 = Tn
now find Tn of this AP
Tn = T₁ + (n-1)d
Tn = 8 + 3n - 3
Tn = 5 + 3n
Answered by
7
a=8
d=11-8=14-11=3
Sn=n/2(2×8+(n-1)3)
=>Sn=n/2(13+3n)
and
Sn-1=n-1/2(16+(n-2)3)
=>Sn-1=n-1/2(10+3n)
find diff u will get ans
d=11-8=14-11=3
Sn=n/2(2×8+(n-1)3)
=>Sn=n/2(13+3n)
and
Sn-1=n-1/2(16+(n-2)3)
=>Sn-1=n-1/2(10+3n)
find diff u will get ans
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