Point-Slope Form In slope-intercept form, we used the _______________ to write an equation of a line. The Point-Slope form of a linear equation is used when you don’t know the _______. Point-Slope Form of a Linear Equation: Given a point 1 1( , )x y and a slope m you can use

the formula: _____________________ to write the equation of a non-vertical line.  

1 1( , )x y  represents a specific point on the graph.  

(x, y) represents any point. Identifying an Equation in Point-Slope Form: A line passes through (1, -4) and has a slope 3. What is an equation of the line?

Examples: Write an equation of the line in slope-intercept form through the given point and with the given slope m.  

1.  (2, 1); m = 3 2.  (–3, –5); m = –2

 

Graphing Using Point-Slope Form: In order to graph the line from point slope form, we need the __________ and the ___________ to plot another point. EXAMPLE: What is the graph of the equation 3 2( 2)y x ?

1) Plot the point 1 1( , )x y

2) Use the slope to find the next point.

3) Draw a line through the two points.

 

 

Using Two Points to Write an Equation: You can write the equation of a line in point slope form given any two points on the line.

EXAMPLE: Write an equation for the line below.

1) Find slope using the slope formula

2) Use point slope form to create an equation

3) Use either point for 1 1( , )x y

 

 

 

Using a Table to Write an Equation:

Model the data in the table with a linear equation in point slope form. What do the slope and y-intercept represent?

        1   1) Find the slope using two points

2) Pick a point to write the equation in Point-Slope form.

3) Rewrite in slope-intercept form.

Examples: Write the equations in Point-Slope Form.

1)                  2)