Question

How do I determine the value of x that makes x-2, x+2, 5, 9,... (arithmetic sequence)?

Answer 1

9-5 = 4
=>5 -(x+2) =4
=>x=-1

Answer 2

common difference is 4
x+2 -(x-2) = 4
5-(x+2) = 4
5-x-2 =4
3-x = 4
x = -1