Answers

2016-02-05T18:49:53+05:30
Natural nos. start from 1 and last term as given by you is 80.
Here, The AP is 1, 2, 3,.......80
Here, a=1, an= 80, d=2-1=1
an=a+(n-1)d
⇒ 80=1+(n-1)1
⇒ 80-1 = n-1
⇒ 79=n-1
⇒ 79+1 = n
⇒ 80=n 
therefore there are 80 terms.

Thank You......!!!!!!!!!
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Yours, Jahnavi.
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2016-02-05T19:43:36+05:30
80 natural numbers. Hope it's correct
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