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Which term of the series -2,0,2,4,..........is 80 and 102 ?

Answers (1)

Given Arithmetic Progression = -2, 0, 2, 4,.........

We have to find which term of the given A. P. is 80 and 102.

⇒ an = a + (n -1)d
Where a = -2
and common difference (d) = 0 - (-2)
= 0 + 2
= 2

Therefore,
80 = -2 + (n - 1)2
80 = -2 + 2n -2
80 + 2 + 2 = 2n
84 = 2n 
n = 84/2
n = 42

So, 80 is 42nd term of the given A.P. 

102 = -2 + (n - 1)2
102 = -2 + 2n -2
102 + 2 + 2 = 2n
106 = 2n
n = 106/2
n = 53

So, 102 is 53rd term of the given A.P.

 

Posted by

Satyajeet Kumar

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