Q. 94.3( 240 Votes )

If the 3rd and th

Answer :

Given, a3 = 4 and a9 = - 8


a3 = a + 2d = 4


a9 = a + 8d = - 8


Subtracting 3rd term from 9th term, we get;


a + 8d – a – 2d = - 8 – 4 = - 12


6d = - 12


d = - 2


Substituting the value of d in 3rd term, we get;


a + 2(-2) = 4


a – 4 = 4


a = 8


Now; 0 = a + (n – 1)d


0 = 8 + (n – 1)(- 2)


(n – 1)(- 2) = - 8


n – 1 = 4


n = 5


Thus, 5th term of this AP is zero.


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