Tony Nguyen
Period 1

Slope Intercept Form Tutorial

 

The standard equation for slope intercept form: y=mx+b

 

 

  y=mx+b

 

 

                                                                                Y-intercept

                                                            Slope

 

Finding the slope

 

  1. http://www.math.com/school/subject2/images/S2U4L2DP1.gifChoose two points
  2. Determine the positions
  3. Substitute the coordinates into the equation above.
  4. This is the slope of the line.

 

Example:

  1. After choosing points A and B, determine their coordinates.
  2. Point A is (1,1) and Point B is (2,3).
  3. Substitute points A and B into the slope equation.
  4.  
  5. http://www.math.com/school/subject2/images/S2U4L2DP3.gif

Point A: x1y1 = (1,1)

Point B: x2y2 = (2, 3)
  1. 2 is the slope of the line.

 

Finding the y-intercept

 

Writing a slope intercept form

  1. Determine the slope of the line (using the slope equation).
  2. Plug the slope into m.
  3. Determine where the line crosses the y-axis. This is the y-intercept.
  4. Plug the y-intercept into b.

 

 

 

Example:

1.      y = (2/3)x - 4First determine the slope.

a.       Point A: (6, 0); Point B: (3, -2)

b.      Plug coordinates into the slope equation.

c.        

2.      Determine the y-intercept

a.       The line crosses the y-axis at -4

3.      Plug in the slope and y-intercept into y=mx+b

4.     

Exceptions

Horizontal

·        When it is a horizontal line, the slope is 0

·        y = 0x+b          y = b   *b = y-intercept*

·        For the graph on right, y = 1

 

Vertical

·        When it is a vertical line, the slope is undefined

·        Since the slope is undefined, the standard form for slope intercept is no longer used,  x = x-intercept is used instead

·        For example, the graph on right would be x = -1

 

 

 

 

Practice Equations