If the nth term of the A.P.is same as the nth term of the A.P.find n.

A=9, D=7-9=-2

a=15, d=-3


An=an


A+(n -1)D=a +(n -1)d


9 – (n -1)2=15 – (n -1)3


(n -1)(3 -2)=6


n -1=6


n=7


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