SOLUTION: Once you have the graph of a line, how can you find its slope? Does it matter which points you choose to find the slope? Does the slope vary depending on your choice of points?

Algebra ->  Linear-equations -> SOLUTION: Once you have the graph of a line, how can you find its slope? Does it matter which points you choose to find the slope? Does the slope vary depending on your choice of points?      Log On


   

Question 132018: Once you have the graph of a line, how can you find its slope? Does it matter which points you choose to find the slope? Does the slope vary depending on your choice of points?
Found 2 solutions by rapaljer, solver91311:
Answer by rapaljer(4671) About Me  (Show Source):
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Find ANY two points on the graph. It doesn't matter which points you use, or which direction you go, as long as they are two distinct points on the line. Then measure the vertical and horizontal distances between the two points. Remember, then that slope is the VERTICAL distance divided by the HORIZONTAL distance. If the line is going UPHILL (up on the right side!), then the slope is positive. If the line is going DOWNHILL (down on the right side!), then the slope is negative.

R^2

Answer by solver91311(24713) About Me  (Show Source):
You can put this solution on YOUR website!
1. Pick two points, any two because the answer to both your other questions is no. Call one of them P%5B1%5D and the other P%5B2%5D, again, it doesn't matter which.

The x- and y-coordinates of P%5B1%5D are x%5B1%5D and y%5B1%5D. Likewise, the x- and y-coordinates of P%5B2%5D are x%5B2%5D and y%5B2%5D.

The formula for the slope of a line given two points is %28%28y%5B1%5D-y%5B2%5D%29%2F%28x%5B1%5D-x%5B2%5D%29%29.

All you need to to is put the coordinate values from the points you selected into the formula and do the arithmetic.

Example: Let's say you chose the points P1(2,4) and P2(1,3), then:





%284-3%29%2F%282-1%29=1%2F1=1, and the slope is 1.