line passing through

Jul 2009
275
43
Melbourne
Use the 2 point formula:

\(\displaystyle \frac {y-y_{1}}{x-x_{1}} = \frac {y_{2}-y_{1}}{x_{2}-x_{1}} \)
 
Mar 2010
71
2
does it matter where i put the numbers
No, it does not as long as it follows the rule.
Say you subbed \(\displaystyle y_2\) with 7
\(\displaystyle y_2\)
Then the numerator must be \(\displaystyle x_2\) from the same point you subbed \(\displaystyle y_2\) first, in this case, it has to be -4.

Regardless which way you put which points in first, you will always get the same answer.

\(\displaystyle \frac{7--3}{-4-1}=-2\)

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\(\displaystyle \frac{-3-7}{1--4}=-2\)

To refrain from getting confused, label the points.
\(\displaystyle (-4,7)\) and \(\displaystyle (1,-3)\)
\(\displaystyle (x_1,y_1)\) and \(\displaystyle (x_2,y_2)\)

or

\(\displaystyle (-4,7)\) and \(\displaystyle (1,-3)\)
\(\displaystyle (x_2,y_2)\) and \(\displaystyle (x_1,y_1)\)
 
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