Chain Rule

Yankel

New member
Joined
Jun 12, 2014
Messages
1
Hello,

I need help with this chain rule problem. I have a function z=f(x,y) for which:

\[f_{x}(0,-3)=3,f_{y}(0,-3)=-2\]

So knowing this, for the function g which defined like this:

\[g(x,y)=f(2ln(x+y),x^{4}-3y^{2})\]

which one of the following statements is correct ?

(1)
\[g_{y}(0,-3)=18\]



(2)
\[g_{y}(0,-3)=-6\]

(3)
\[g_{y}(0,1)=-6\]

(4)
\[g_{y}(0,1)=18\]

(5)
None of the answers above

Thank you !
 
The correct answer is (5) "does not exist" because g(0, -3) itself does not exist. x+ y= 0+ -3= -3 so ln(x+y) does not exist.
 
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