Download 5.3 Write Linear Equations in Point-Slope Form

5.3 Write Linear Equations in Point-Slope Form
Big Idea:
-Verify that a point lies on a line, given an equation of a line.
-Derive linear equations by using the point-slope formula.
Previously you learned one strategy for writing a linear equation when
given the slope and a point on the line. In this lesson you will learn a
different strategy – one that uses the point-slope form of an equation
of a line.
What we Know so far….
Slope Intercept Form: y = mx + b
The New Stuff… Point- Slope Form
The point-slope form of the equation of the nonvertical line through a
given point (y1 , x1 )with slope of m is:
y  y1  m(x  x1 )
Again, where m is the slope and (y1 , x1 ) is a point on the line.
Example: Write an equation in point-slope form.
•
(1) Write an equation in point-slope form of the line that passes
through the point (-1, 4) and has a slope of -2.
(2) Write an equation in point-slope form of the line that passes
through the point (-3, 1) and has a slope of 3.
Using Point-Slope
Write an equation in point-slope form:
Find the slope of the line:
Write the equation in point-slope form.
Use the point (2, 2):
•
Graph an equation in point-slope form:
(1) Graph the equation y - 1 = -(x - 2)
) Graph the equation
1
y  2  (x  2)
2
Write an equation in point-slope form of the line shown:
Find the slope of the line:
(-1, 3)
(1, 1)
Write the equation in point-slope form.
You can use either given point.
Example 2: Write in point-slope form:
Find the slope of the line:
(-2, 3)
Write the equation in point-slope form.
You can use either given point.
(1, -3)
Extra Example:
•
Write an equation in point-slope form of the line that passes
through the points (2, 3) and (4, 4).