Do each one at a time and add them after you are done is necessary, first multiply 2x times x^3 this gives 2x^4. Then multiply 1 times x^3 to get x^3. Then multiply 2x times -1 to get -2x. Then multiply -1 and +1 to get -1. Then combine them together. None of the terms are like terms so you don't need to worry about combining them further but keep that in mind for other problems. The final answer becomes 2x^4 + X^3 - 2x -1 because none of the terms are the same power.
