Explanation:
The formula isnt correctly written, it should state:
You have to start from and end in a³+b³. On your first step, you need to use the distributive property.
This is equal to
Note that the second term, -a²b, is cancelled by the fourth term, ba², and the third term, ab², is cancelled by the fifht term, -b²a. Therefore, the final result is a³+b³, as we wanted to.