Question

a=-18.9,d=2.0,n=?,an=3.6​

Answer 1

Answer:

n=10

Step-by-step explanation:

Here, a=−18.9,d=2.5 and a  

n  =3.6.

Therefore, a  n

=a+(n−1)d

−18.9+(n−1)×2.5=3.6

⇒(n−1)×2.5=22.5

⇒n−1=9

∴n=10

Answer 2

Step-by-step explanation:

an = a + (n-1)d

= 18.9 + 2n - 2

= 16.9 + 2n

3.6 - 16.9 = 2n

13.3 = 2n

6.65 = n