Chapter 11: Problem 68
If \(\lim _{(x, y) \rightarrow(2,3)} f(x, y)=4,\) can you conclude anything about \(f(2,3) ?\) Give reasons for your answer.
Chapter 11: Problem 68
If \(\lim _{(x, y) \rightarrow(2,3)} f(x, y)=4,\) can you conclude anything about \(f(2,3) ?\) Give reasons for your answer.
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Get started for freeUse the function $$f(x, y)=3-\frac{x}{3}-\frac{y}{2}$$ Find \(D_{\mathbf{u}} f(3,2),\) where \(\mathbf{u}=\frac{\mathbf{v}}{\|\mathbf{v}\|}\) (a) \(\mathbf{v}\) is the vector from (1,2) to (-2,6) . (b) \(\mathbf{v}\) is the vector from (3,2) to (4,5) .
Moment of Inertia An annular cylinder has an inside radius of \(r_{1}\) and an outside radius of \(r_{2}\) (see figure). Its moment of inertia is \(I=\frac{1}{2} m\left(r_{1}^{2}+r_{2}^{2}\right)\) where \(m\) is the mass. The two radii are increasing at a rate of 2 centimeters per second. Find the rate at which \(I\) is changing at the instant the radii are 6 centimeters and 8 centimeters. (Assume mass is a constant.)
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Show that the function is differentiable by finding values for \(\varepsilon_{1}\) and \(\varepsilon_{2}\) as designated in the definition of differentiability, and verify that both \(\varepsilon_{1}\) and \(\varepsilon_{2} \rightarrow 0\) as \((\boldsymbol{\Delta x}, \boldsymbol{\Delta} \boldsymbol{y}) \rightarrow(\mathbf{0}, \mathbf{0})\) \(f(x, y)=x^{2} y\)
In your own words, give a geometric description of the directional derivative of \(z=f(x, y)\).
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