We can expand our answer and compare it with the given expression.
w^2 (w +1) (w - 1)
(w^3 +w^2) (w - 1)
w(w^3 +w^2) - (w^3 +w^2)
w^4 + w^3 - (w^3 + w^2)
w^4 + w^3 - w^3 -w^2
w^4 -w^2
We can see above that after expanding and simplifying, the result is the same as the given expression. Therefore, we can be sure our solution is correct!