Question

I just need the answer for b​

Answer 1

For an nth term in an arithmetic sequence

U(n) = a + ( n-1)d

a = first term

d = common difference

n = number of terms.

Considering the above picture

a = 9

d = 6 - 9 = - 3

For an nth term of the sequence

U(n) = 9 + (n - 1)-3

= 9 - 3n + 3

= 12 - 3n

Hope this helps