Question

What is the 20th term of the following arithmetic sequence?
1/2 , 1 , 3/2, 2

Answer 1

hello :
the common diffrence is : 2-3/2 =3/2-1 = 1-1/2 =1/2
an = a1 +(n-1)d    (general term)    a1 =1/2   d=1/2
an = 1/2+(n-1)(1/2) = 1/2n
if n =20 a20 = (1/2)(20) = 10