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

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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?