Graph $\displaystyle y = -x-3$ by using the slope and $y$-intercept.
$y$-intercept:
$
\begin{equation}
\begin{aligned}
y =& -x-3
&& \text{Given equation}
\\
y =& 0-3
&& \text{To find the $y$-intercept, let } x = 0
\\
y =& -3
&&
\end{aligned}
\end{equation}
$
The $y$-intercept is $(0,-3)$
$
\begin{equation}
\begin{aligned}
m =& \frac{\text{change in } y}{\text{change in } x}
\\
\\
m =& \frac{-1}{1}
\\
\\
m =& -1
\end{aligned}
\end{equation}
$
Beginning at the $y$-intercept, move to the right 1 unit and then down 1 unit.
$(1, -4)$ are the coordinates of a second point on the graph.
Draw a line through $(0,-3)$ and $(1, -4)$
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