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Example

Finding the Slope of the Line Between (1,2)(1, 2) and (4,5)(4, 5)

To find the slope of the line passing through the points (1,2)(1, 2) and (4,5)(4, 5), apply the slope formula.

Label the points. Let (1,2)(1, 2) be point #1 so that x1=1x_1 = 1 and y1=2y_1 = 2, and let (4,5)(4, 5) be point #2 so that x2=4x_2 = 4 and y2=5y_2 = 5.

Write the slope formula:

m=y2y1x2x1m = \frac{y_2 - y_1}{x_2 - x_1}

Substitute the coordinates. First replace the yy-values in the numerator, then the xx-values in the denominator:

m=5241m = \frac{5 - 2}{4 - 1}

Simplify the numerator and the denominator:

m=33m = \frac{3}{3}

Simplify the fraction:

m=1m = 1

The slope is 11. This result can be confirmed on a graph by counting the rise and run between the two points: using m=riserunm = \frac{\text{rise}}{\text{run}}, the line rises 33 units and runs 33 units to the right, giving 33=1\frac{3}{3} = 1. It does not matter which point is designated as point #1 and which as point #2 — swapping the labels produces the same slope.

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Updated 2026-04-21

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