Question

The 17th term of an A.P. is 5 more than twice its 8th term. If the 11th term of the A.P. is 43, find the nth term.

Answer 1

Answer:

4n-1

Step-by-step explanation:

Answer 2

Nth term of the AP = 4n-1

Step-by-step explanation:

Given: 17th term of an A.P. is 5 more than twice its 8th term.  

 11th term of the A.P. is 43.

Find: the nth term.

Solution:

an = a +(n-1)d

a11 = 43

a + 10d = 43 -------(1)

a17 = 5 +a8

a + 16d = 5 + 2(a+ 7d)

a + 16d = 5 + 2a+ 14d

a -2d = -5 ------(2)

Subtracting (2) from (1), we get: +12d = 48

Therefore d = +4

Substituting d in (1), we get: a + 40 = 43

Therefore a = 3

Nth term of the AP = 3 + (n-1)4 = 3 + 4n - 4 = 4n-1