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2 years ago

Can some one help me plss

Mathematics

1 answer:

Thepotemich [5.8K]2 years ago

6 0

Irrational

Rational

Irrational

Rational

Irrational

Sorry if anything is wrong, I went off of memory! :)

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Evaluate the surface integral S F · dS for the given vector field F and the oriented surface S. In other words, find the flux of

tresset_1 [31]

Because I've gone ahead with trying to parameterize $S$ directly and learned the hard way that the resulting integral is large and annoying to work with, I'll propose a less direct approach.

Rather than compute the surface integral over $S$ straight away, let's close off the hemisphere with the disk $D$ of radius 9 centered at the origin and coincident with the plane $y=0$ . Then by the divergence theorem, since the region $S\cup D$ is closed, we have

$\displaystyle\iint_{S\cup D}\vec F\cdot\mathrm d\vec S=\iiint_R(\nabla\cdot\vec F)\,\mathrm dV$

where $R$ is the interior of $S\cup D$ . $\vec F$ has divergence

$\nabla\cdot\vec F(x,y,z)=\dfrac{\partial(xz)}{\partial x}+\dfrac{\partial(x)}{\partial y}+\dfrac{\partial(y)}{\partial z}=z$

so the flux over the closed region is

$\displaystyle\iiint_Rz\,\mathrm dV=\int_0^\pi\int_0^\pi\int_0^9\rho^3\cos\varphi\sin\varphi\,\mathrm d\rho\,\mathrm d\theta\,\mathrm d\varphi=0$

The total flux over the closed surface is equal to the flux over its component surfaces, so we have

$\displaystyle\iint_{S\cup D}\vec F\cdot\mathrm d\vec S=\iint_S\vec F\cdot\mathrm d\vec S+\iint_D\vec F\cdot\mathrm d\vec S=0$

$\implies\boxed{\displaystyle\iint_S\vec F\cdot\mathrm d\vec S=-\iint_D\vec F\cdot\mathrm d\vec S}$

Parameterize $D$ by

$\vec s(u,v)=u\cos v\,\vec\imath+u\sin v\,\vec k$

with $0\le u\le9$ and $0\le v\le2\pi$ . Take the normal vector to $D$ to be

$\vec s_u\times\vec s_v=-u\,\vec\jmath$

Then the flux of $\vec F$ across $S$ is

$\displaystyle\iint_D\vec F\cdot\mathrm d\vec S=\int_0^{2\pi}\int_0^9\vec F(x(u,v),y(u,v),z(u,v))\cdot(\vec s_u\times\vec s_v)\,\mathrm du\,\mathrm dv$

$=\displaystyle\int_0^{2\pi}\int_0^9(u^2\cos v\sin v\,\vec\imath+u\cos v\,\vec\jmath)\cdot(-u\,\vec\jmath)\,\mathrm du\,\mathrm dv$

$=\displaystyle-\int_0^{2\pi}\int_0^9u^2\cos v\,\mathrm du\,\mathrm dv=0$

$\implies\displaystyle\iint_S\vec F\cdot\mathrm d\vec S=\boxed{0}$

8 0

3 years ago

What is the y coordinate of the point that divides the

svet-max [94.6K]

Answer:

the y coordinate is 5

Step-by-step explanation:

In the figure attached, the directed line segment is shown.

J is located at (-3, 1) and K is located at (-8, 11)

run: x2 -x1 = -8 - (-3) = -5

rise: y2 - y1 = 11 - 1 = 10

Taking J as reference, the coordinate of the point that divides the directed line segment from J to k into a ratio of 2:3 is:

c = 2/(2+3) = 0.4

(x1 + c*run, y1 + c*rise)

(-3 + 0.4*-5, 1+0.4*10)

(-5, 5)

6 0

3 years ago

As a first step in solving the system shown, Yumiko multiplies both sides of the equation 2x – 3y = 12 by 6. By what factor shou

GenaCL600 [577]

Answer:

Yumiko should multiply the other equation by 3.

If she adds the two equations she would be left with the variable 'x'.

Step-by-step explanation:

Given the two equations are as follows:

$2x - 3y = 12 \hspace{5mm} \hdots (1)$

$5x + 6y = 18 \hspace{5mm} \hdots (2)$

It is given that she multiplies the first equation by 6. Therefore, (1) becomes

$12x - 18y = 72 \hspace{15mm} \hdots (a)$

Now, note that the sign of the variable 'y' is negative. So, if we make the co-effecient of 'y' equal in both the cases, add them it would result in the elimination of the variable 'y'.

The co-effecient of y in Equation (2) is 6. To make it 18 like it is in Equation (1), we multiply throughout by 3.

Therefore, Equation (2) becomes:

$15x + 18y = 54 \hspace{5mm} \hdots (b)$

Now, we add Equation (a) and Equation (b).

$\implies 12x - 18y + 15x + 18y = 72 + 54$

$\implies 27x = 126$

Factor: 3

Equation: 27x = 126

7 0

2 years ago

The angle of parallelogram is 12 less than 5 times the measure of these angle

Y_Kistochka [10]

let one angle be X

so, other angle be 5x-12

ATQ

X+5x-12=180

6x=180-12

6x=168

X=168/6

hence X=28

now,one angle=28

other angle is 5×28-12

= 140-12.

= 128

5 0

2 years ago

Please I really need help with these

MrRissso [65]

Answer:

Idk lol

Step-by-step explanation:

8 0

3 years ago