2 o
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An equation of a line can be written in the slope-intercept form:
y = mx + b. The slope of the line is m and the y-intercept is b.
The y-intercept is the y-coordinate of the point where the line
crosses the y-axis.
Example: For y = - 3x - 1, the slope is -3. The y-intercept is -1.
Use the graph to write an equation for the line through (-1,2) and
(0, -1).
1 Find m: slope change in x
change in y-2
2 Find b: y-intercept = -1
y-intercept
3 In the equation y = mx + b, substitute m = -3 and b = -1.
The equation for the line is y = - 3r - 1.