Answers

2014-06-12T06:01:25+08:00
Given,
P_1(13,2)
P_2(9,1)
P_3(x,-3)

Formula:

m= \frac{y_2-y_1}{x_2-x_1}

solution:

First get the slope from P_1 to P_2

m= \frac{1-2}{9-13}

m= \frac{1}{4}

then, solve for the x:

m= \frac{-3-1}{x-9}

\frac{1}{4}= \frac{-3-1}{x-9}

x-9=4(-3-1)

x=-7

checking 

\frac{y_2-y_1}{x_2-x_1}=\frac{y_3-y_2}{x_3-x_2}

 \frac{1}{4} = \frac{-3-1}{-7-9}

 \frac{1}{4} = \frac{1}{4}
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