Question

in an AP the sum of first n terms is 3n square +13n/2 . Find the 25th term
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Answer 1

Answer:

a25=475/2

Step-by-step explanation:

general formula given=3n^2+13n/2

then, S1= 3(1)+13(1/2)

=>S1= 19/2

a=19/2

=>S2=3(2)+13(1)

=19

So, d=S2-S1

d=19/2

Then, a25= 19/2+24x19/2

=>a25=475/2

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