# How do you combine ( 4r^3+3r^4)-(r^4-5r^3)?

Apr 3, 2018

$2 {r}^{4} + 9 {r}^{3}$

So here's what I did:

#### Explanation:

$\left(4 {r}^{3} + 3 {r}^{4}\right) - \left({r}^{4} - 5 {r}^{3}\right)$

First, you distribute the $-$ to everything in its parenthesis:
$4 {r}^{3} + 3 {r}^{4} - {r}^{4} + 5 {r}^{3}$

Now we combine like terms.
$4 {r}^{3} + 5 {r}^{3} = 9 {r}^{3}$

$3 {r}^{4} - {r}^{4} = 2 {r}^{4}$

So the combined format is $2 {r}^{4} + 9 {r}^{3}$.

Hope this helps!