I need to know how to simplify this?
1) Open up parentheses. If there is '+' sign in front, just drop parentheses and keep signs of all terms inside unchanged. Otherwise, if there is '-' sign in front, drop parentheses and that '-' sign and change sign of every term inside parentheses.
In your case,
2) Now collect like terms, that is terms with the same powers of x. In your case those are:
-2x3 and 3x3; 4x and -x; -2 and 4.
Here I underlined like terms and marked them with different colors.
Combining like terms is done like this:
I took common factor (x3 in this case) out using distributive property of multiplication.
Similarly, 4x-x=3x and -2+4=2.
So, the final result is: