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#### Slope Of A Line Through Two Points:

A. To find
the slope of a line through 2 points, (x_{0},y_{0})
and (x_{1},y_{1}),
use the following formula:

B. Notice,
it does not matter if you subtract y_{1} - y_{0}
or y_{0} - y_{1} as
long as you are consistent with the x-values also. In other words, if you
subtract y_{0} - y_{1}
you should subtract x_{0} - x_{1}.

C.
Examples

Ex [1]
Find the slope of the line passing through the points (6,-1) and (4, 5).
________.

a. First,
subtract the y-values: 5 - (-1) = 6.

b.
Subtract the x-values: 4 - 6 = -2.

c. The
answer is -^{6}/_{2} = -3.

Ex [2]
Find the slope of the lines passing through the points (1,1) and (-2,3).
________.

a. First,
subtract the y-values: 1 - 3 = -2.

b.
Subtract the x-values: 1 - (-2) = 3.

c. The
answer is -^{2}/_{3}.

D.
Sometimes the question might ask for the perpendicular slope of a line passing
through the two points. In this case, simply find the *negative
reciprocal*. So for Ex [1] the perpendicular slope would be ^{1}/_{3}
and for Ex [2] the perpendicular slope would be ^{3}/_{2}.

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