Mathematics
Answer
Given,
a4 = 9
⇒ a + (4 - 1)d = 9
⇒ a + 3d = 9
⇒ a = 9 - 3d ……..(1)
Given,
Sum of a6 + a13 = 40
⇒ a + (6 - 1)d + a + (13 - 1)d = 40
⇒ a + 5d + a + 12d = 40
⇒ 2a + 17d = 40 ……(2)
Substituting value of a from equation (1) in equation (2), we get :
⇒ 2(9 − 3d) + 17d = 40
⇒ 18 − 6d + 17d = 40
⇒ 18 + 11d = 40
⇒ 11d = 22
⇒ d = 2.
Substituting the value of d in equation (1), we get :
⇒ a = 9 - 3(2)
⇒ a = 9 - 6
⇒ a = 3.
So the A.P. is,
3, 5, 7, 9, 11, ….
Hence, A.P is 3, 5, 7, 9, 11, …..
Related Questions
In an A.P. the first term is 25, nth term is -17 and the sum of n terms is 132. Find n and the common difference.
If 18, a and (b - 3) are in A.P., then find the value of (2a - b).
The sum of n natural numbers is 5n2 + 4n. Find its 8th term.
The fourth term of an A.P. is 11 and the eight term exceeds twice the fourth term by 5. Find the A.P. and the sum of first 50 terms.