Question

Find the number of Terms in AP 6, 3,0 3, , ... by using formula an=a+(n-1) d .
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Answer 1

Given A.P : 6,3,0,3,.... , -36.

a= 6 , d = 3-6 = -3 , an = -36

an = a+(n-1) d

-36 = 6 +( n-1)( -3)

-36 -6 = (n-1) (-3)

- 42 = (n−1)(−3)

-42 / -3 = n-1

=> n-1 = -42/-3

=> n-1 = 14

=> n = 15

Hence, the number of the terms in the given AP is 15

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