Q3 of 85 Page 101

Find the nth term of the following A.P.'s:

200, 195, 190, 185, ...

Formula Used.


dn = an + 1 – an


an = a + (n–1)d


In the above sequence,


a = 200;


d1 = a2–a1 = 195–200 = –5


d2 = a3–a2 = 190–195 = –5


d3 = a4–a3 = 185–190 = –5


The difference in sequence is same and comes to be (–5).


∴ The above sequence is A.P


The nth term of A.P is an = a + (n–1)d


an = a + (n–1)d = 200 + (n–1)(–5)


= 200–5n + 5


= 205–5n


More from this chapter

All 85 →
2

Determine if the following sequences represent an A.P., assuming that the pattern continues. If it is an A.P., find the nth term:

Natural numbers which are multiples of 3 or 5 in increasing order.

 3

Find the nth term of the following A.P.'s:

2, 7, 12, 17, ...

 3

Find the nth term of the following A.P.'s:

1000, 900, 800, ...

 3

Find the nth term of the following A.P.'s:

50, 100, 150, 200, ...