Question

8) If for any A.P. d = 5, then t 18
-t 13 = .......​

Answer 1

Question :

If for any A.P. d = 5, then t₁₈  - t₁₃ = ......

Answer :

t₁₈  - t₁₃ = 25

Step-by-step explanation :

Given :

d = 5

To find :

t₁₈  - t₁₃ = ?

Solution :

In an A.P.,

nth term is given by,

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

where

a denotes first term

d denotes common difference

We have to find the value of t₁₈  - t₁₃

First, find 18th term and then 13th term,

18th term :

n = 18

d = 5

t₁₈  = a + (18 - 1)(5)

t₁₈  = a + 17(5)

t₁₈  = a + 85

13th term :

n = 13

d = 5

t₁₃ = a + (13 - 1)(5)

t₁₃ = a + 12(5)

t₁₃ = a + 60

⇒ t₁₈  - t₁₃

     = a + 85 - (a + 60)

     = a + 85 - a - 60

     = 85 - 60

     = 25

Therefore, t₁₈  - t₁₃ = 25