Chapter 3 - Introduction to Graphing - 3.7 Point-Slope Form and Equations of Lines - 3.7 Exercise Set - Page 219: 71

$y=-2x-1$

Using $y-y_1=\dfrac{y_1-y_2}{x_1-x_2}(x-x_1)$ or the Two-Point Form, then the equation of the line passing through the given points, $( 2,-5 )\text{ and }( 0,-1 )$, is \begin{array}{l} y-(-5)=\dfrac{-5-(-1)}{2-0}(x-2) \\\\ y+5=\dfrac{-5+1}{2}(x-2) \\\\ y+5=\dfrac{-4}{2}(x-2) \\\\ y+5=-2(x-2) \\\\ y+5=-2x+4 \\\\ y=-2x+4-5 \\\\ y=-2x-1 .\end{array}