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richyw Group Title

having a little bit of trouble remembering how to do the differential.

  • 2 years ago
  • 2 years ago

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  1. richyw Group Title
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    so I have \(k(x,y,z)=e^{x^2+y^2+z^2}\) where \(x=\sqrt{t+1},\;y=\sqrt{t^2+1},\:z=\sqrt{t^3+1}\) . Now i need to find \(\frac{dk}{dt}\).

    • 2 years ago
  2. richyw Group Title
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    to do this do I just say\[\frac{dk}{dt}=\frac{dk}{dx}\frac{dx}{dt}+\frac{dk}{dy}\frac{dy}{dt}+\frac{dk}{dz}\frac{dz}{dt}\]

    • 2 years ago
  3. richyw Group Title
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    I am getting an answer of \[\frac{dk}{dt}=2e^{t^3+t^2+t+3}\left(3t^2+2t+1\right)\] is this correct, and does anyone know how to check this on wolfram, or open-source math software?

    • 2 years ago
  4. eseidl Group Title
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    The formula for the total differential is correct, as long as the dk/dx,etc terms are partial derivatives.

    • 2 years ago
  5. richyw Group Title
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    yeah sorry I didn't want to type "partial" \(\partial\) in the latex that many times :)

    • 2 years ago
  6. richyw Group Title
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    thanks a lot. can anyone confirm this is the correct answer?

    • 2 years ago
  7. eseidl Group Title
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    this one is super tedious...give me a minute I'll do it with pen and paper...

    • 2 years ago
  8. richyw Group Title
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    alright thanks a lot. I really appreciate it.

    • 2 years ago
  9. eseidl Group Title
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    I get:\[e^{t^3+t^2+t+3}(3t^2+2t+1)\]

    • 2 years ago
  10. eseidl Group Title
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    Your factor of two should cancel when you differentiate the square root term (which gives you a 2 in the denominator)...

    • 2 years ago
  11. richyw Group Title
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    thanks a lot! I see I made a basic calculus mistake but am glad I remember this stuff!

    • 2 years ago
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