Prime Notation

To enter the prime symbol, you can click on the ' button located on standard keyboards or on the Desmos keyboard under FUNCTIONS and Misc.

 

 

To use prime notation for derivatives, first try defining a function using f(x) notation. f'(x) can then be used to graph the first order derivative of f(x). Use f''(x) to find the second derivative and so on. Note that depending on the complexity of f(x), higher order derivatives may be slow or non-existent to graph. If the derivative evaluates to a constant, the number is shown in the expression list instead of on the graph. In some cases, you may want to use d/dx notation for derivatives.

 

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7 Comments

  • 0
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    白雪

    thanks.It's realy what i want to use in my lessons.

  • 0
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    白雪

    kristin,i am david.i am a math teacher in beijing china.Can i ask your help? i want to find if i can use the desmos to get the minimum value of a function?

  • 0
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    Prof Lassonde

    Hi David,

    I think this is the article your are looking for:

    http://support.desmos.com/hc/en-us/articles/202528969-Points-of-Interest-intercepts-intersections-and-more

    Hope this helps!

  • 0
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    Brent Ferguson

    I'd like to set up an exploration of a Taylor series. But I can't seem to find a way to notate an abstract "nth derivative" in Desmos, so that I can write y = sum of [ (nth deriv of f at a) * (x-a)^n / n! ] and then let n be a slider...

    It works well enough for functions with clean and predictable derivatives, like cos(x), sin(x), and e^x... but I'd like to use it also for any arbitrary differentiable function. Any ideas?

  • 0
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    T Chip Webb

    @白雪 Pretty sure it isn't possible to find minima automatically. You can use method Prof Lassonde suggests, though.

    Also f'(x)=0 draws a vertical line(s) through f(x) minima/maxima.

    Earlier today, I submitted a suggestion for a "root" function which would return a function's root(s). If "root" were implemented you could find the minima/maxima of f(x) as follows: root(f'(x)) or root(f'(x){0<=x<=1}) to find minima/maxima in range zero to one.

  • 0
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    Brent Ferguson

    But can DESMOS accept the "nth derivative" as a notation? That is, f^(n)[x]  (the nth derivative of f) instead of f^n[x]  (the nth power of f), the way we'd write it on paper? I'd like to tell it "n prime marks" and let n be a user-input slider. Any suggestions for that?

  • 0
    Avatar
    T Chip Webb

    @白雪 Pretty sure it isn't possible to find minima automatically. You can use method Prof Lassonde suggests, though.

    Also f'(x)=0 draws a vertical line(s) through f(x) minima/maxima.

    Earlier today, I submitted a suggestion for a "root" function which would return a function's root(s). If "root" were implemented you could find the minima/maxima of f(x) as follows: root(f'(x)) or root(f'(x{0<=x<=1})) to find minima/maxima in range zero to one.

    Edited by T Chip Webb
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