Question

Choose the correct simplification of (2x3 + x2 − 4x) − (9x3 − 3x2).

11x3 − 2x2 − 4x

−7x3 + 4x2 − 4x

−2x3 − 2x2 − 4x

−7x3 − 4x2 − 4x

Answer 1

\[ (2x^3 + x^2 − 4x) − (9x^3 − 3x^2)\] distribute the minus sign and get
\[2x^3+x^2-4x-9x^3+3x^2\] and then combine like terms

Answer 2

\[2x^3-9x^3=-7x^3\] and \[x^2+3x^2=4x^2\]so you get
\[-7x^3+4x^2-4x\]