Question

وه
a= -18.9
d=2.5
n= ?
an=36
​

Answer 1

The value of n is 10.

Explanation:

Given, a = - 18.9, d = 2.5 and aₙ= 3.6

We must know that,

aₙ = a + (n - 1) d

or, 3.6 = - 18.9 + (n - 1) (2.5)

or, 3.6 = - 18.9 + 2.5 n - 2.5

or, 2.5 n = 3.6 + 18.9 + 2.5

or, 2.5 n = 25

or, n = 25 / 2.5

or, n = 10

Therefore, the value of n is 10.