How to Use Chain Rule to Find Second Derivative of Multivariable Functions?

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SUMMARY

The discussion focuses on applying the chain rule to compute the second derivative of multivariable functions, specifically for the function F(x,y) where y=y(t) and x=x(t). The correct formulation for the second derivative, Ftt, is established as Ftt = (Fxx*xt + Fxy*yt)*xt + Fx*xtt + (Fyx*xt + Fyy*yt)*yt + Fy*ytt. Participants confirm the necessity of including mixed partial derivatives F_xy and F_yx in the calculations, emphasizing the use of both the product rule and chain rule in this context.

PREREQUISITES
  • Understanding of multivariable calculus concepts, specifically derivatives.
  • Familiarity with the chain rule and product rule in calculus.
  • Knowledge of partial derivatives and their notation (e.g., Fxx, Fxy, Fyx, Fyy).
  • Basic proficiency in differentiating functions of multiple variables.
NEXT STEPS
  • Study the application of the chain rule in multivariable calculus.
  • Learn about mixed partial derivatives and their significance in multivariable functions.
  • Explore examples of second derivatives in multivariable contexts.
  • Review the product rule and its application in conjunction with the chain rule.
USEFUL FOR

Students and professionals in mathematics, particularly those studying calculus, as well as educators teaching multivariable calculus concepts.

TranscendArcu
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Suppose I have

F(x,y) and y=y(t) and x=x(t)

Therefore,

Ft = Fx*xt + Fy*yt. Right?

Can I write

Ftt = (Fxx*xt + Fyy*yt)*xt + Fx*xtt + (Fxx*xt + Fyy*yt)*yt + Fy*ytt

?

Basically I'm trying to figure out the second derivative by chain rule.
 
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Shouldn't there be some F_xy's and F_yx's in there?
 
You're right. I meant to write:


Ftt = (Fxx*xt + Fxy*yt)*xt + Fx*xtt + (Fyx*xt + Fyy*yt)*yt + Fy*ytt
 
TranscendArcu said:
You're right. I meant to write:


Ftt = (Fxx*xt + Fxy*yt)*xt + Fx*xtt + (Fyx*xt + Fyy*yt)*yt + Fy*ytt

Looks ok now, good job. Just product rule and chain rule, yes?
 

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