# How do you combine like terms (-3y^2-7y-9)-(4y^2+6y+9)?

Jan 9, 2017

See process for combining like terms below:

#### Explanation:

First, remove the parenthesis from the terms paying close attention to the sign of each individual term:

$\left(- 3 {y}^{2} - 7 y - 9\right) - \left(4 {y}^{2} + 6 y + 9\right) \to$

$- 3 {y}^{2} - 7 y - 9 - 4 {y}^{2} - 6 y - 9$

Next we will group the like terms together:

$- 3 {y}^{2} - 4 {y}^{2} - 7 y - 6 y - 9 - 9$

Now we can combine like terms:

$\left(- 3 - 4\right) {y}^{2} + \left(- 7 - 6\right) y + \left(- 9 - 9\right)$

$\left(- 7\right) {y}^{2} + \left(- 13\right) y + \left(- 18\right)$

$- 7 {y}^{2} - 13 y - 18$