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Question

Mathematics for Economy Question on Differential Equations

Let fR2Rf ∶ R^2 → R be a function defined as
f(x,y)={x2yx4+Y2if(x,y)(0,0) 0if(x,y)=(0,0)f(x,y) =\begin{cases}\frac{x^2y}{x^4 + Y^2} & if (x, y) \neq (0, 0)\\\ 0 & if (x, y) = (0, 0)\end{cases} Then, which of the following is/are CORRECT?

A

lim(x,y)(0,0)𝑓(x,y)=0 \lim_{(x,y) \rightarrow (0,0)} 𝑓(x, y) = 0

B

fx(0,0)=0f_x(0, 0) = 0

C

𝑓(x, y) is not continuous at (0, 0)

D

Both fxf_x and fyf_y do not exist at (0, 0)

Answer

fx(0,0)=0f_x(0, 0) = 0

Explanation

Solution

The correct Options are B and C : lim(x,y)(0,0)𝑓(x,y)=0 \lim_{(x,y) \rightarrow (0,0)} 𝑓(x, y) = 0 AND 𝑓(x, y) is not continuous at (0, 0)