In an AP the sum of first n terms is given by Sn = 3n2/2 + 5n2/2. Find it's 25the term.
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Sn=3n^2/2+5n^2/2
putting n=1
S1=3*1*1/2+5*1*1/2
=8/2
=4
s1=a1
putting n=2
s2=3*2*2/2+5*2*2/2
=12+20/2
=32/2
=16
a2=S2-S1
=16-4
=12
d=a2-a1
=12-4
=8
ap is
4,12,20.......
a25=a+24d
4+24*8
=196
hope it helps u:D
putting n=1
S1=3*1*1/2+5*1*1/2
=8/2
=4
s1=a1
putting n=2
s2=3*2*2/2+5*2*2/2
=12+20/2
=32/2
=16
a2=S2-S1
=16-4
=12
d=a2-a1
=12-4
=8
ap is
4,12,20.......
a25=a+24d
4+24*8
=196
hope it helps u:D
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