Question 971418
it's actually A2 plus (A2 minus A1).


you would find the difference between A1 and A2 and then add that to the value that's in A2 in order to get the value that's in A3.


that would make the differnece linear, i.e. an arithmetic progression.


for A4, youwould use A3 plus (A3 minus A2).


you would get the same common d9ifference.


for example:


A1 = 5
A2 = 10
A3 = A2 + (A2 - A1) = 10 + (10-5) = 10 + 5 = 15
A4 = A3 + (A3 - A2) = 15 + (15-10) = 15 + 5 = 20
etc.


you would have:
A1 = 5
A2 = 10
A3 = 15
A4 = 20
etc.