Green's theorem says the circulation of $\vec F$ along the rectangle's border $C$ is equal to the integral of the curl of $\vec F$ over the rectangle's interior $D$ .

Given $\vec F(x,y)=2xy\,\vec\imath$ , its curl is the determinant

$\det\begin{bmatrix}\frac\partial{\partial x}&\frac\partial{\partial y}\\2xy&0\end{bmatrix}=\dfrac{\partial(0)}{\partial x}-\dfrac{\partial(2xy)}{\partial y}=-2x$

So we have

$\displaystyle\int_C\vec F\cdot\mathrm d\vec r=\iint_D-2x\,\mathrm dx\,\mathrm dy=-2\int_0^3\int_0^8x\,\mathrm dx\,\mathrm dy=\boxed{-192}$

6 0

3 years ago

If you have 20 coins worth $1.35, and you only have nickels and dimes, how many do you have of each coin?

ankoles [38]

N + d = 20....n = 20 - d
0.05n + 0.10d = 1.35

0.05(20 - d) + 0.10n = 1.35
1 - 0.05d + 0.10d = 1.35
-0.05d + 0.10d = 1.35 - 1
0.05d = 0.35
d = 0.35/0.05
d = 7 <==== 7 dimes

n + d = 20
n + 7 = 20
n = 20 - 7
n = 13 <=== 13 nickels

5 0

3 years ago

Find the value of x<br> (x +40)<br> x

gayaneshka [121]

Answer: x^2 + 40x

Nothing can further be done with the topic.....

8 0

3 years ago

Under what condition the composite function of any two function is an identity function?

Veseljchak [2.6K]

Answer:

under the condition of f(x)=x composite function is an identity one

6 0

3 years ago