Hello, Makall!

Show that the polynomial interpolating the following data has degree three.

I am not familiar with "Newton's forward-difference formula",

. . but I'm sure it is similar to the following.

Take the differences of consecutive terms,

. . then take the differences of the differences, and so on.

Since thedifferences are constant,third

. . the generating function is of thedegree (a cubic).third

Your function is correct . . . Good work!