Q5 of 202 Page 9

Show that the sequence defined by is not A.P.

Put n = 1

A1= 3(1)2 – 5 = 3 – 5 = -2


Put n = 2


A2= 3(2)2 – 5 = 12- 5 = 7


Put n = 3


A3= 3(3)2 – 5 = 27 – 5 = 22


Common difference, d1= a2 – a1 =7 – (-2) = 9


Common difference, d2 = a3 – a2 = 22 – 9 = 13


Since, d1 ≠ d2


Therefore, it’s not an A.P.


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3

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Find the common difference and write the next four terms of each of the following arithmetic progressions:

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(ii)


(iii)


(iv)