☰
✕

Arithmetic Progressions
Question
Wired Faculty App

Determine the A .P. whose 3rd term is 5 and the 7th term is 9.

Answer

We have, a3 = 5
⇒ a + (3 – 1) d = 5
⇒ a + 2d = 5 ...(i)
and a7 = 9
⇒ a + (7– n) d = 9
⇒ a + 6d = 9 ...(ii)
Subtracting (i) from (ii), we get
(a + 6d) – (a + 2d) = 4
⇒ a + 6d – a – 2d = 4
⇒ 4d = 4
⇒ d = 1
Putting the value of ‘d’ in (i), we get
a + 2d = 5 ⇒ a + 2(1) = 5
⇒ a + 2 = 5 ⇒ a = 3
Hence, the required A .P. be 3, 4, 5, 6, 7,..........

Sponsor Area

Some More Questions From Arithmetic Progressions Chapter

Write first four terms of the AP, when the first term a and the common difference d are given as follows:
a = 4, d = – 3

Write first four terms of the AP, when the first term a and the common difference d are given as follows:

a = – 1.25, d = – 0.25

For the following APs, write the first term and the common difference
3, 1, – 1, – 3, . . .

For the following APs, write the first term and the common difference
– 5, – 1, 3, 7, . . .

For the following APs, write the first term and the common difference
0.6, 1.7, 2.8, 3.9, . . .

Which of the following are APs ? If they form an AP, find the common difference d and write three more terms.
– 1.2, – 3.2, – 5.2, – 7.2, . . .