Example

Verifying the Slope and y-Intercept of y=2x+1y = 2x + 1 from its Graph

To demonstrate the connection between a line's graph and its slope-intercept form, the slope and y-intercept of y=2x+1y = 2x + 1 can be read directly from the graph and then compared to the equation.

The graph passes through the points (0,1)(0, 1) and (1,3)(1, 3).

Step 1 — Find the slope from the graph. Starting at (0,1)(0, 1) and moving to (1,3)(1, 3), count the rise and run:

m=riserun=21=2m = \frac{\text{rise}}{\text{run}} = \frac{2}{1} = 2

Step 2 — Find the y-intercept from the graph. The line crosses the y-axis at the point (0,1)(0, 1).

Step 3 — Compare to y=mx+by = mx + b. The values found from the graph are slope m=2m = 2 and y-intercept (0,1)(0, 1). Looking at the equation y=2x+1y = 2x + 1:

  • The coefficient of xx is 22, which matches the slope.
  • The constant term is 11, which matches the y-coordinate of the y-intercept.

This confirms that when a linear equation is written in slope-intercept form, the coefficient of xx is always the slope that can be measured from the graph, and the constant term is always the y-coordinate of the point where the line crosses the y-axis.

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Updated 2026-04-21

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