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Math Help - Slope of Lines

  1. #1
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    Slope of Lines

    For years, I have heard that the slope of vertical lines is undefined (does not exist) and the slope of horizontal lines is zero but no clear and/or easy explanation has ever been given by a teacher or professor in my experience.

    Why is the slope of vertical lines undefined and at the same time, why is the slope of horizontal lines zero?

    Please, no technical, textbook-like answers.
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  2. #2
    A riddle wrapped in an enigma
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    Quote Originally Posted by magentarita View Post
    For years, I have heard that the slope of vertical lines is undefined (does not exist) and the slope of horizontal lines is zero but no clear and/or easy explanation has ever been given by a teacher or professor in my experience.

    Why is the slope of vertical lines undefined and at the same time, why is the slope of horizontal lines zero?

    Please, no technical, textbook-like answers.
    Hello magentarita,

    Let's just talk about the definition of slope. It's the change in y divided by the change in x.

    slope=\frac{\Delta y}{\Delta x}

    In a vertical line, there is no change in x. It remains constant. Therefore,

    slope=\frac{\Delta y}{0} = undefined (dividing by zero is undefined)

    And in a horizontal line, there is no change in y. So,

    slope=\frac{0}{\Delta x}=0
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  3. #3
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    ok....

    Quote Originally Posted by masters View Post
    Hello magentarita,

    Let's just talk about the definition of slope. It's the change in y divided by the change in x.

    slope=\frac{\Delta y}{\Delta x}

    In a vertical line, there is no change in x. It remains constant. Therefore,

    slope=\frac{\Delta y}{0} = undefined (dividing by zero is undefined)

    And in a horizontal line, there is no change in y. So,

    slope=\frac{0}{\Delta x}=0
    Very simply put. Thank you very much. Merry Christmas.
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