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Unformatted text preview: he equation for the vertical line in the fourth part is x=4 The next special form of the line that we need to look at is the point-slope form of the line. This
form is very useful for writing down the equation of a line. If we know that a line passes through
the point ( x1 , y1 ) and has a slope of m then the point-slope form of the equation of the line is, y - y1 = m ( x - x1 )
Sometimes this is written as, y = y1 + m ( x - x1 )
The form it’s written in usually depends on the instructor that is teaching the class.
As stated earlier this form is particularly useful for writing down the equation of a line so let’s
take a look at an example of this. Example 2 Write down the equation of the line that passes through the two points ( -2, 4 ) and ( 3, -5 ) .
At first glance it may not appear that we’ll be able to use the point-slope form of the line since
this requires a single point (we’ve got two) and the slope (which we don’t have). However, that
fact that we’ve got two points isn’t really a...
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- Spring '12