How do you simplify (-12x^3+5x-23)-(4x^4+31-9x^3)?

Jun 6, 2018

$= - 4 {x}^{4} - 3 {x}^{3} + 5 x - 54$

Explanation:

In order to simplify you need to add the like terms.

Remove the brackets first.

$\left(- 12 {x}^{3} + 5 x - 23\right) \textcolor{red}{- \left(4 {x}^{4} + 31 - 9 {x}^{3}\right)}$

$= - 12 {x}^{3} + 5 x - 23 \textcolor{red}{- 4 {x}^{4} - 31 + 9 {x}^{3}} \text{ } \leftarrow$ note the signs

$= - 4 {x}^{4} - 12 {x}^{3} + 9 {x}^{3} + 5 x - 23 - 31 \text{ } \leftarrow$ re-arrange

$= - 4 {x}^{4} - 3 {x}^{3} + 5 x - 54 \text{ } \leftarrow$ add like terms