Chapter 13: Problem 5
To which coordinate axes are the following cylinders in \(\mathbb{R}^{3}\) parallel: \(x^{2}+2 y^{2}=8, z^{2}+2 y^{2}=8,\) and \(x^{2}+2 z^{2}=8 ?\)
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Chapter 13: Problem 5
To which coordinate axes are the following cylinders in \(\mathbb{R}^{3}\) parallel: \(x^{2}+2 y^{2}=8, z^{2}+2 y^{2}=8,\) and \(x^{2}+2 z^{2}=8 ?\)
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Limits at (0,0) may be easier to evaluate by converting to polar coordinates. Remember that the same limit must be obtained as \(r \rightarrow 0\) along all paths to (0,0) Evaluate the following limits or state that they do not exist. $$\lim _{(x, y) \rightarrow(0,0)} \frac{(x-y)^{2}}{x^{2}+x y+y^{2}}$$
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Use the definition of differentiability to prove that the following functions are differentiable at \((0,0) .\) You must produce functions \(\varepsilon_{1}\) and \(\varepsilon_{2}\) with the required properties. $$f(x, y)=x y$$
Use the formal definition of a limit to prove that $$\lim _{(x, y) \rightarrow(a, b)}(f(x, y)+g(x, y))=\lim _{(x, y) \rightarrow(a, b)} f(x, y)+$$ $$\lim _{(x, y) \rightarrow(a, b)} g(x, y)$$
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