Q9 of 102 Page 429

If 7th and 13th terms of an AP be 34 and 64 respectively then find its 18th term.

Given: 7th term is 34 and 8th term is 64


To find: find its 18th term


34 = a + 6d ………….equation1


64 = a + 12d ………… equation2


Subtract equation1 from equation2 we get


d = 5


Put in equation1 we get


a = 4


So 18th term is


4 + 17 × 5 = 89


More from this chapter

All 102 →
7

Find the 8th term from the end of the AP 7, 9, 11, …., 201.

 8

How many 2 - digit numbers are divisible by 7?

 10

What is the 10th common term between the APs 3, 7, 11, 15, 19, … and 1, 6, 11, 16, …?

 11

The first and last terms of an AP are 1 and 11 respectively. If the sum of its terms is 36, find the number of terms.