# How do you find the slope and intercept of x+y=9?

Feb 8, 2017

$\text{slope "=-1" and y-intercept } = 9$

#### Explanation:

The equation of a line in $\textcolor{b l u e}{\text{slope-intercept form}}$ is

$\textcolor{red}{\overline{\underline{| \textcolor{w h i t e}{\frac{2}{2}} \textcolor{b l a c k}{y = m x + b} \textcolor{w h i t e}{\frac{2}{2}} |}}}$
where m represents the slope and b, the y-intercept.

$\text{Rearrange " x+y=9" into this form}$

subtract x from both sides of the equation.

$\cancel{x} \cancel{- x} + y = 9 - x$

$\Rightarrow y = - x + 9 \leftarrow \textcolor{red}{\text{ in slope-intercept form}}$

$\Rightarrow \text{slope "=m=-1" and y-intercept } = b = 9$