It is given that the sum of the first n terms of an A.P. is 3n2+6n. Calculate the nth term of this A.P.
ML Aggarwal Avichal Publication Arithmetic Progression Chapter 9 Question 16
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The sum of the first n terms of an A.P. is 3n2 + 6n. Find the nth term of this A.P.
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sn=3n2+6n
sn−1=3(n−1)2+6(n−1)
sn−1=3(n2−2n+1)+6n−6
sn−1=3(n2−2n+1)+6n−6
sn−1=3n2−6n+3+6n−6
sn−1=3n2−3
tn=sn−sn−1
tn=3n2+6n−3n2+3
tn=6n+3