Slope-intercept form. Equation of a straight line.

For an online calculator for straight-lines, go to http://matrixlab-examples.com/equation-of-a-straight-line.html

How to write the slope-intercept form of a straight line.

If you know that the slope of a line is m and the y-intercept is b, then the slope-intercept equation is
y = mx + b

The slope is the difference of the vertical distance of two given points, divided by their horizontal difference.

For horizontal lines the slope is 0. For vertical lines the slope is undefined.

In this example we know the y-intercept and the slope of a line. The slope is -3... the point is (0, -2). Thus, the slope-intercept expression is y = -3x -2

In this other example, we know 2 points but we must calculate the slope. After the calculations, we discover that the slope is 2. We also know that the y-intercept is 5. This means that the slope-intercept equation is y = 2x + 5

In this last example, we're given the y-intercept and we can easily calculate the slope. The y-intercept is 7 and the slope is 3. Then, the slope-intercept equation is y = 3x + 7.

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