Q28 of 178 Page 559

The 17th term of an AP exceeds its 10th term by 21. The common difference of the AP is

Let a be the first term and d be the common difference.

Given: a₁₇ = a₁₀ + 21

To find: common difference = d

Consider a₁₇ = a₁₀ + 21

⇒ a + 16d = a + 9d + 21

⇒ 16d = 9d + 21

⇒ 16d - 9d = 21

⇒ 7d = 21

⇒ d = 3

∴ Common difference = 3

How many terms of the AP 3, 7, 11, 15, ... will make the sum 406?

The 2nd term of an AP is 13 and its 5th term is 25. What is its 17th term?

The 8th term of an AP is 17 and its 14th term is 29. The common difference of the AP is

The 7th term of an AP is 4 and its common difference is - 4. What is its first term?