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What is the formula for parametric second derivatives? watch

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    Lost a notebook containing the formula and can't remember it to save my life..
    Your help would be appreciated...
    zazy
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    dy/dx = dy/dt dt/dx = (dy/dt)/(dx/dt)

    d²y/dx² = d/dx (dy/dx)

    = dt/dx d/dt(dy/dx)

    = dt/dx d/dt[(dy/dt)/(dx/dt)]
    = dt/dx [dx/dt d²y/dt² - dy/dt d²x/dt²]/(dx/dt)²

    = [dx/dt d²y/dt² - dy/dt d²x/dt²]/(dx/dt)³

    (i hope thats right, im doing it on the fly)
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    (Original post by elpaw)
    dy/dx = dy/dt dt/dx = (dy/dt)/(dx/dt)

    d²y/dx² = d/dx (dy/dx)

    = dt/dx d/dt(dy/dx)

    = dt/dx d/dt[(dy/dt)/(dx/dt)]
    = dt/dx [dx/dt d²y/dt² - dy/dt d²x/dt²]/(dx/dt)²

    = [dx/dt d²y/dt² - dy/dt d²x/dt²]/(dx/dt)³

    (i hope thats right, im doing it on the fly)
    As far as i can trace it's correct... you're a lifesaver....I'll strangle my friend...
 
 
 

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