Question

I really need help with this equation as soon as possible :D

Answer 1

The subtraction sign in front of the second set of parenthesis changes the signs on the terms inside those parenthesis.  So this could be rewritten as  $x-3x^4+2x^2+x^3-4x^6$.  None of the exponents on the x are the same, so we will just express it in terms of descending powers of x.   $-4x^6-3x^4+x^3+2x^2+x$.   This is also the same as  $4x^6+3x^4-x^3-2x^2-x$  if you don't like to start with a negative.  Either one is correct.