Susanne217

Remember if we have two points in the xy-plane which fits on a straight line which has the formula [tex]y = ax+b[/tex] then the formula for finding the slope is

[tex]a = \frac{y_2 - y_1}{x_2 - x_1}[/tex]

Proof

Let [tex](x_1,y_1)[/tex] and [tex](x_2,y_2)[/tex] be points in the plane which we believe to fit a straight line which has the formula
[tex]y=ax+b[/tex] then inserting these points respectively into the formula gives us.

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Back in High School I learned the following

If you have to equations on the form

[itex]y = a \cdot x + b[/itex] then to show then they have a commen (x,y) or more generelly they intersect then one had to go through the process of making the two linear equation equation each other and isolate the commen x and y. This was in my opinion a very tidious procedure where some of my fellow classmates often made errors. Then I became an undergraduate student I learned about...