Evaluating limit of 2 variable function

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tmt1
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I have

$$\lim_{{(x, y)}\to{(0, 0)}} \frac{x^4 - y^4}{x^4 + x^2y^2 + y^4}$$

If I evaluate the limit along the x-axis, I get

$$\lim_{{(x, y)}\to{(0, 0)}} \frac{x^4 - y^4}{x^4 + x^2y^2 + y^4}$$

which evaluates to $1$.

If I evaluate the limit along the y-axis, I get

$$\lim_{{y}\to{0}} \frac{ - y^4}{ y^4}$$

which evaluates to $-1$.

Since the 2 limits are different, then the limit does not exist. Is this correct?
 
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