Answer:

nth term of the A.P 13, 8, 3, -2, ….

Arithmetic Progression (AP) whose common difference is = a_n – a_n-1 where n > 0

Consider,

a = a₁ = 13, a₂ = 8 …

Common difference, d = a₂ – a₁ = 8 – 13 = -5

Find a_n

a_n = a + (n-1) d

= 13 + (n-1) (-5)

= 13 – 5n + 5

= 18 – 5n

n^th term is 18 – 5n