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Example

Finding the Slope 13-\frac{1}{3} on a Geoboard

A rubber band is stretched between two pegs on a geoboard, creating a line that falls from left to right. To determine its slope, a right triangle is formed starting at the left peg.

Using the slope definition m=riserunm = \frac{\text{rise}}{\text{run}}, count the vertical and horizontal distances from the left peg to the right peg:

  • The line drops 11 unit downward, so the rise is 1-1.
  • The line moves 33 units to the right, so the run is 33.

Substituting into the formula:

m=13=13m = \frac{-1}{3} = -\frac{1}{3}

The slope is 13-\frac{1}{3}, which means the line drops 11 unit for every 33 units of horizontal distance. Because the rise is negative (the line goes downward from left to right), the slope is negative.

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Updated 2026-04-21

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