Q8 of 89 Page 49

Justify whether it is true to say that the following are the nth terms of an AP.

1 + n + n2

Put n = 1, 2, 3, 4


We get


a1 = 1 + 1 + (1)2 = 3


a2 = 1 + 2 + (2)2 = 7


a3 = 1 + 3 + (3)2 = 13


a4 = 1 + 4 + (4)2 = 21


List of AP is 3, 7, 13, 21. . . .


a2 - a1 = 7 - 3 = 4


a3 - a2 = 13 - 7 = 6


As


a3 - a2 is not equal to a2 - a1


the list is not an AP


More from this chapter

All 89 →
8

Justify whether it is true to say that the following are the nth terms of an AP.

2n – 3

 8

Justify whether it is true to say that the following are the nth terms of an AP.

 1

Match the AP’s given in column A with suitable common differences given in column B.




















































Column A




Column B



(A1)



2, - 2 – 6, - 10, …



(B1)





(A2)



a = - 18, n = 10, an = 0



(B2)



–5



(A3)



a = 0, a10 = 6



(B3)



4



(A4)



a2 = 13, a4 = 3



(B4)



–4





(B5)



2





(B6)







(B7)



5


 2

Verify that each of the following is an AP and then write its next three terms.