Hey there!
You can use distributive property, as I mentioned in your previous questions.
multiply...
2a² × a = 2a³
2a² × -1 = -2a²
a × a = a²
a × -1 = -a
3 × a = 3a
3 × -1 = -3
add all those terms..
2a³ - 2a² + a² - a + 3a - 3
add the like terms
2a³ - a² + 2a - 3
Hope this helped :)