Question

The nth term of an AP is an=2n+1 , find its sum
we can find
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Answer 1

Answer:

If the nth term of an AP is an=2n+1

then,

first term=2(1)+1

=2+1

=3

second term=2(2)+1

=4+1

=5

common difference= 5-3

= 2

sum of an AP is=n/2(2a+(n-1)d)

=n/2(2(3)+(n-1)2)

=n/2(6+2n-2)

=n/2(4+2n)

=n(2+n)

=2n+n2(square)

sum of the AP is 2n+n2.