SOLUTION: I do not understand how to use the substitution method to find an intersection point. I have (-6,1) (5,4) and (5,-4) (-6,4). If I write the equation in standard form is it -6A +

Algebra ->  Graphs -> SOLUTION: I do not understand how to use the substitution method to find an intersection point. I have (-6,1) (5,4) and (5,-4) (-6,4). If I write the equation in standard form is it -6A +       Log On


   



Question 249905: I do not understand how to use the substitution method to find an intersection point. I have (-6,1) (5,4) and (5,-4) (-6,4). If I write the equation in standard form is it -6A + 1B=C?
Answer by solver91311(24713) About Me  (Show Source):
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An equation of the line that passes through two points and is derived using the two-point form:




For your first set of points:



A little arithmetic and less algebra gets us to the standard form of the equation:



(verification of the last step is an exercise for the student)

Perform the same process for your second set of points. Then, to use the substitution process, you need to solve one of your equations for either of the variables in terms of the other, thus:








Then substitute (hence the name of the method) the expression on the left for the variable on the right in the other equation. That will leave you with a single equation in a single variable that you can solve by ordinary means.

John