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class
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Point-Slope Form
In order to write the equation of a line in point-slope form, it is necessary to know the slope of the
line and the coordinates of at least one point on the line.
Point-Slope Form: y 2 y1 5 m(x 2 x1)
m tells the
slope of the
line.
x1 and y1 give the
coordinates of a point
(x1, y1) on the line.
Example A
Write the equation, in point slope form, of the line passing through the points (3, 22) and (7, 24).
24 2(22)
723
22
m5
4
1
m 52
2
m5
y 2 y 1 5 m( x 2 x 1)
1
y 2 (22) 52 ( x 2 3)
2
1
y 1 2 52 ( x 2 3)
2
Step 1: Determine the slope of the line using the
y 2y
slope formula: m 5 2 1 .
x 22x 1
Step 2: Use point-slope form, the slope of the line
and one of the points on the line, to write the
equation of the line.
Practice
1. Write the equation, in point-slope form, of the line passing through the points (7, 12)
and (10, 11).
2. Write the equation, in point-slope form, of the line passing through the points (22, 1)
and (3, 24). 3. Use point-slope form to write the equation, in slope-intercept form, of the line passing
through (23, 1) and (2, 0).
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SpringBoard Mini-Lesson, Algebra 1 Unit 2