Finite differences

[Audentes]

Did I reach a dead end? The last problem went fine for me, but I can't find the same numbers on this one.

UPDATE: NEVERMIND!! I found that I was subtracting backward but then subtracted forward on one of the brackets. Careless error ?

 

[Steven G]

The last problem went fine for me, but I can't find the same numbers on this one.
Why would you expect to get the same numbers on this problem as you did on the last problem?