☰
✕

Arithmetic Progressions
Question
Wired Faculty App

If 9th term of an A .P. is zero. Prove that 29th term is double of its 19th term. 

Answer

 Let a be the first term and d be the common difference of the A .P. we have,
a9 = 0 ⇒ a + 8d = 0 ⇒ a = – 8d
Now, a29 = a + 28d = –8d + 28d = 20d
2(a19) = 2(a + 18d) = 2(– 8d + 18d)
= 2(10d) = 20d
Hence, a29 = 2 (a19)

Sponsor Area

Some More Questions From Arithmetic Progressions Chapter

In which of the following situational, does the list of numbers involved make an arithmetic progression, and why?

The cost of digging a well for the first metre is Rs. 150 and rises by Rs. 50 for each succeeding metre.

In which of the following situational, does the list of numbers involved make an arithmetic progression, and why?

The taxi fare after each km when the fare is Rs. 15 for the first km and Rs. 8 for each additional km.

In which of the following situational, does the list of numbers involved make an arithmetic progression, and why?

The cost of digging a well for the first metre is Rs. 150 and rises by Rs. 50 for each succeeding metre.

Write first four terms of the AP, when the first term a and the common difference d are given as follows:
a – 10, d = 10

Write first four terms of the AP, when the first term a and the common difference d are given as follows:
a = –2, d = 0

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