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3 years ago

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Mathematics

1 answer:

Orlov [11]3 years ago

7 0

If order matters, then there are 12 ways to do this

If order does not matter, then there are 6 ways to do this

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We have 4 choices for the first slot and 3 choices for the next (we can't reuse a letter) so that's where 4*3 = 12 comes from

If order doesn't matter, then something like AB is the same as BA. So we are doubly counting each possible combo. To fix this, we divide by 2: 12/2 = 6

To be more formal, you can use nPr and nCr to get 12 and 6 respectively (use n = 4 and r = 2)

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If f is a scalar field and F, G are vector fields, then f F, F · G, and F × G are defined by the following. (f F)(x, y, z) = f(x

valentina_108 [34]

Answer:

Step-by-step explanation:

Consider curl $(fF)$ where $f$ is a scalar function and F is a vector function

$F=F_{1}i +F_{2}j +F_{3}k$

i j k

$curl(fF) = \frac{\partial}{\partial x}$ $\frac{\partial}{\partial y}$ $\frac{\partial}{\partial z}$

$fF_{1}$ $fF_{2}$ $fF_{3}$

$curl(fF)=i(\frac{\partial}{\partial y}(fF_{3})-\frac{\partial}{\partial z}(fF_{2}))-j(\frac{\partial}{\partial x}(fF_{3})-\frac{\partial}{\partial z}(fF_{1}))+k(\frac{\partial}{\partial x}(fF_{2})-\frac{\partial}{\partial y}(fF_{1}))$

$=i(\frac{\partial}{\partial y}(F_{3})+\frac{\partial}{\partial y}(f)-\frac{\partial}{\partial z}(F_{2})-\frac{\partial}{\partial z}(f))-j(\frac{\partial}{\partial x}(F_{3})+\frac{\partial}{\partial x}(f)-\frac{\partial}{\partial z}(F_{1})-\frac{\partial}{\partial z}(f))+k(\frac{\partial}{\partial x}(F_{2})+\frac{\partial}{\partial x}(f)-\frac{\partial}{\partial y}(F_{1})-\frac{\partial}{\partial y}(f))$

$curl(fF)=f(\Delta\times F)+(\Delta f)\times F$

3 0

3 years ago

The long-distance calls made by the employees of a company are normally distributed with a mean of 6.3 minutes and a standard de

Sergio [31]

To solve this problem, we use the formula:

z = (x – u) / s

where z is the z score value which can be obtained from the tables, x is the sample value, u is the mean = 6.3 min, and s is the std dev = 2.2 min

at P value = 0.90, the z = 1.28, finding for x:

x = z s + u

x = 1.28 * 2.2 + 6.3

x = 9.116

at P value = 1.0, the z = 3.49, finding for x:

x = z s + u

x = 3.49 * 2.2 + 6.3

x = 13.978 ~ 14

Therefore the longest 10% calls last about 9.1 minutes to 14 minutes

3 0

4 years ago

Regina recently inherited an oil painting that was purchased by her great-grandfather for $100 in 1938. In 2013 she took the pai

muminat

The future worth of a certain item or money deposited at a certain percentage is obtained by the equation,

F = P x (1 + i)^n

F is the future worth, P is present worth, i is the percentage, and n is the number of years.

n = 2013 - 1938
n = 75

Substituting the known values,

300,000 = 100 x (1 + i)^75

The value of i from the equation is 0.1126.

The answer to this item is 11.26%.

6 0

3 years ago

Read 2 more answers

Fourteen is 6 less a number (n). Which equation shows this relationship?

Klio2033 [76]

Answer:

14+6=n=20

Step-by-step explanation:n=20

8 0

3 years ago

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A ratio of boys to girls in the classroom is 4 to 5 if there are 20 girls how many boys would there be

Viktor [21]

Answer:

16 to 20

Step-by-step explanation:

Let's do our math.

4 to 5

8 to 10

12 to 15

16 to 20

In order to get to 20, you'd have to multiply 5 by 4. So in order to get an equal ratio, you multiply 4 by 4 and get 16.

I hope this helps!

-No one

8 0

2 years ago