Math 344: Calculus III




Unit IV Exam: Review Guide


This page contains problems similar to those that will appear on the in class portion of the Unit IV Exam. These questions are all similar to ones that you encountered while doing your WebAssign homework.


1. Evaluate the integral \(\displaystyle \int_C x\, ds\) where \(C\) is the arc of the parabola \(y = x^2\) from \((1,1)\) to \((0,0)\).

2. Evaluate the integral \(\displaystyle \int_C y^3 \, dx + x^2 \, dy\) where \(C\) is the arc of the parabola \(x = 1-y^2\) from \((0,-1)\) to \((0,1)\).

3. Compute \(\displaystyle \int_C \mathbf{F}\cdot d\mathbf{r}\) where \(\mathbf{F}(x,y,z) = \langle e^z,xz,(x+y)\rangle\) and \(C\) is given by \(\mathbf{r}(t) = \langle t^2,t^3,-t\rangle\).

4. Show that \(\mathbf{F}\) is a conservative vector field, then find a potential function, \(f\). \[\mathbf{F}(x,y) = (1+xy)e^{xy}\mathbf{i} + (e^y + x^2e^{xy})\mathbf{j}\]

5. Show that \(\mathbf{F}\) is conservative and use that fact to evaluate \(\displaystyle \int_C \mathbf{F}\cdot d\mathbf{r}\). \[\begin{cases} \mathbf{F}(x,y,z) = \langle e^y,xe^y+e^z,ye^z\rangle, \\ C \mathrm{\ is\ the\ line\ segment\ from\ } (0,2,0)\ \mathrm{to\ } (4,0,3). \end{cases}\]

6. Verify Green's Theorem is true for the line integral \[\int_C xy^2\, dx - x^2y\, dy \] where \(C\) consists of the parabola \(y = x^2\) from \((-1,1)\) to \((1,1)\) and the line segment from \((1,1)\) to \((-1,1)\).

7. Use Green's Theorem to evaluate the path integral, where \(C\) is the positively oriented triangle with vertices \((0,0), (1,0),\) and \((1,3)\). \[\displaystyle \int_C \sqrt{1 + x^3}\,dx + 2xy\, dy \]

8. Find \(\mathrm{curl\ }\mathbf{F}\) and \(\mathrm{div\ }\mathbf{F}\) for \[\mathbf{F}(x,y,z) = e^{-x}\sin y\, \mathbf{i} + e^{-y}\sin z\, \mathbf{j} + e^{-z}\sin x\, \mathbf{k}. \]

9. Suppose \(f\) is a harmonic function: \(\Delta f = 0\). Show that \[ \displaystyle \int_C \dfrac{\partial f}{\partial y}\, dx - \dfrac{\partial f}{\partial x}\, dy = 0 \] where \(C\) is any simple closed curve in the domain of \(f\).




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