Question
The sum of r terms of an AP is 2r2+3r. The nth term is ___.
Answer: Option B
:
B
Given, Sr=(2r2+3r), the sum upto r terms of an AP.
We know that the nth term of AP is
Tn=Sn−Sn−1.
⇒Sn=2n2+3n and
Sn−1=2(n−1)2+3(n−1).
∴Tn=Sn−Sn−1
=2n2+3n−[2(n2−2n+1)+3n−3]
=2n2+3n−2n2+4n−2−3n+3=4n+1
Was this answer helpful ?
:
B
Given, Sr=(2r2+3r), the sum upto r terms of an AP.
We know that the nth term of AP is
Tn=Sn−Sn−1.
⇒Sn=2n2+3n and
Sn−1=2(n−1)2+3(n−1).
∴Tn=Sn−Sn−1
=2n2+3n−[2(n2−2n+1)+3n−3]
=2n2+3n−2n2+4n−2−3n+3=4n+1
Was this answer helpful ?
More Questions on This Topic :
Latest Videos
Latest Test Papers
Submit Solution