Question

13,11,9,7... In this AP which term number is -5 ?​

Answer 1

Question :

13,11,9,7... In this AP which term number is -5 ?

Answer :

10th term

Given :

13,11,9,7.., are in AP

To find :

which term number is -5?

Solution :

 

Let nth term be -5

     Given AP,

      13,11,9,7,...

In this AP,

a = 13

d = 11-13 = 9-11 = -2

aₙ = -5

n = ?

  where

a is the first term

d is the common difference

aₙ is the nth term

We know that,

nth term is given by,

$\boxed{\bf a_n=a+(n-1)d}$

Substitute the values in the above formula,

⇒ -5 = 13 + (n-1)(-2)

⇒ -5 - 13 = -2n + 2

⇒ -18 = -2n + 2

⇒ 2n = 2 + 18

⇒  2n = 20

⇒  n = 20/2

⇒ n = 10

║∴ 10th term is -5