Question

three terms of an arithmetic sequence are shown below. Which recursive formula defines the sequence? f(1) = 6, f(4) = 12, f(7) = 18 f (n + 1) = f(n) + 6

Answer 1

a = 6
tn = a + (n - 1)d
t4 = 6 + 3d = 12
3d = 12 - 6 = 6
d = 6/3 = 2
f(n + 1) = f(n) + 2

Answer 2

the answer is f(n + 1) = f(n) + 2