Equations with Two Variables: Equations of Lines
Last hour’s graphing of points and lines from equations with an x and a y variable showed you one way to find many ordered pairs that are true for a given equation. Plotting the intercepts allowed you to draw the line that contains each equation’s solutions.
This hour you will learn how to use a line’s slope and key points to write that line’s equation—in some ways, the reverse of the process you learned last hour—along with how to solve real-life problems about direct and inverse variation.
Finding the Equation of a Line from the Slope and y-Intercept
The graph of the equation y - 2x = 6 follows. When x = 0, y = 6, and when y = 0, x = -3. These two key points are the ordered pairs ...