Algebra/Determining Slope

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Algebra
Table of Contents

[edit] Determining Slope

To determine the slope you need some information. This can include two (or more) coordinates, a parallel slope and a coordinate, a perpendicular slope and a coordinate, or the y-intercept and slope.

[edit] Finding It

For the most part finding slope when given information is a simple matter. Simply take the slope equation y=mx+b and replace the variable with whatever information you know, and solve.

[edit] Two Coordinates

To find the slope with two coordinates, you must first find the slope. Use the standard equation \frac{y_1-y_2}{x_1-x_2}. Put that into the equation as m, and replace x and y with x and y from one of the coordinates. Solve for b. Put that into the equation and your done.

Example: (1,4) (4,8)

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

m = \frac{4-1}{4-8}

m = \frac{3}{-4}

Plug that right in.

y = \frac{3}{-4}x+b

4 = \frac{3}{-4}(1)+b

4 = \frac{3}{-4}+b

4-\frac{3}{-4} = b

\frac{-19}{4} = b

Put that in the equation and you're done.

y = \frac{3}{-4}x + \frac{-19}{4}

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