PLS SOMEBODY HELP BEFORE I CRY, {the area of a square is 64n36 square units. what is the side length of one side of the square}

Let f(x,y,z) = ztan-1(y2) i + z3ln(x2 + 1) j + z k. find the flux of f across the part of the paraboloid x2 + y2 + z = 3 that li

Sophie [7]

Consider the closed region $V$ bounded simultaneously by the paraboloid and plane, jointly denoted $S$ . By the divergence theorem,

$\displaystyle\iint_S\mathbf f(x,y,z)\cdot\mathrm dS=\iiint_V\nabla\cdot\mathbf f(x,y,z)\,\mathrm dV$

And since we have

$\nabla\cdot\mathbf f(x,y,z)=1$

the volume integral will be much easier to compute. Converting to cylindrical coordinates, we have

$\displaystyle\iiint_V\nabla\cdot\mathbf f(x,y,z)\,\mathrm dV=\iiint_V\mathrm dV$
$=\displaystyle\int_{\theta=0}^{\theta=2\pi}\int_{r=0}^{r=1}\int_{z=2}^{z=3-r^2}r\,\mathrm dz\,\mathrm dr\,\mathrm d\theta$
$=\displaystyle2\pi\int_{r=0}^{r=1}r(3-r^2-2)\,\mathrm dr$
$=\dfrac\pi2$

Then the integral over the paraboloid would be the difference of the integral over the total surface and the integral over the disk. Denoting the disk by $D$ , we have

$\displaystyle\iint_{S-D}\mathbf f\cdot\mathrm dS=\frac\pi2-\iint_D\mathbf f\cdot\mathrm dS$

Parameterize $D$ by

$\mathbf s(u,v)=u\cos v\,\mathbf i+u\sin v\,\mathbf j+2\,\mathbf k$
$\implies\mathbf s_u\times\mathbf s_v=u\,\mathbf k$

which would give a unit normal vector of $\mathbf k$ . However, the divergence theorem requires that the closed surface $S$ be oriented with outward-pointing normal vectors, which means we should instead use $\mathbf s_v\times\mathbf s_u=-u\,\mathbf k$ .

Now,

$\displaystyle\iint_D\mathbf f\cdot\mathrm dS=\int_{u=0}^{u=1}\int_{v=0}^{v=2\pi}\mathbf f(x(u,v),y(u,v),z(u,v))\cdot(-u\,\mathbf k)\,\mathrm dv\,\mathrm du$
$=\displaystyle-4\pi\int_{u=0}^{u=1}u\,\mathrm du$
$=-2\pi$

So, the flux over the paraboloid alone is

$\displaystyle\iint_{S-D}\mathbf f\cdot\mathrm dS=\frac\pi2-(-2\pi)=\dfrac{5\pi}2$

6 0

2 years ago

Lynn wants to serve hamburgers at her birthday party if hamburger buns are sold in packages of 8 and hamburger patties are sold

WARRIOR [948]

everyone will get 2 burgers i got this answer by multiplying 8 and 6 and then i divided it by 24 and i got 2

hope it helps

3 0

2 years ago

Jonah is going to the store to buy candles. Small candles cost $2.50 and large candles cost $7.00. He needs to buy at least 20 c

artcher [175]

The system of linear inequalities are:

$a + b \geq 20\\\\2.50a + 7b\leq 80$

Solution:

Let "a" be the number of small candles bought

Let "b" be the number of large candles bought

He needs to buy at least 20 candles

Therefore, number of small candles and number of large candles bought must be at least 20

Thus, we frame a inequality as:

$a + b \geq 20$

"at least" means greater than or equal to

Here, we used "greater or equal to" symbol because, he can buy 20 candles or more than 20 candles also

From given,

Cost of 1 small candle = $ 2.50

Cost of 1 large candle = $ 7

He can spend no more than 80 dollars

Which means, he spend maximum 80 dollars or less than 80 dollars also

So we have to use "less than or equal to" symbol

Thus, we frame a inequality as:

Number of small candles bought x Cost of 1 small candle + number of large candles bought x Cost of 1 large candle $\leq$ 80

$a \times 2.50 + b \times 7 \leq 80\\\\2.50a + 7b\leq 80$

Thus the system of linear inequalities are:

$a + b \geq 20\\\\2.50a + 7b\leq 80$

3 0

2 years ago

Ben and Ella are filling goodie bags for a party. Each goodie bag needs an eraser, a bubble wand, and a few candy bar bites. Ben

maxonik [38]

Answer:

Ben

Step-by-step explanation:

25 goodies = 20 minutes

27 goodies = 24 minutes

Let's use ratio, divide both of them by their minute

25/20 = 20/20

27/24 = 24/24

1.25 goodies = 1 minute

1.12 goodies = 1 minute

1.25 is bigger than 1.12.

7 0

2 years ago

F(x) = 3 - 2x and g(x) = 1/X+5 what is the value of (f/g)(8)

Nina [5.8K]

9514 1404 393

Answer:

(f/g)(8) = -104/41

Step-by-step explanation:

Fill in the value for x and do the arithmetic.

f(8) = 3 -2·8 = 3 -16 = -13

g(8) = 1/8 +5 = (1+40)/8 = 41/8

Then the ratio is ...

(f/g)(8) = f(8)/g(8) = -13/(41/8) = -13(8)/41

(f/g)(8) = -104/41

8 0

2 years ago