Answer
$−x^3+4x^2−4x−9$
Work Step by Step
$(x^2-3x-4)-(x^3-3x^2+x+5)$
To simplify, first distribute the negative sign to the contents of the parentheses on the right side.
$(x^2-3x-4)-x^3+3x^2-x-5$
Now remove the remaining parentheses, and combine like terms.
$x^2-3x-4-x^3+3x^2-x-5$=
$−x^3+4x^2−4x−9$
