Please need help asap!

Consider two vectors A and B A=14i and B= -4i+8j

DaniilM [7]

Assuming $\mathbf a,\mathbf b\in\mathbb R^3$ , you have

$\mathbf a\cdot\mathbf b=(14)(-4)+(0)(8)=-56$

so

$((\mathbf a\cdot\mathbf b)\,\mathbf i)\cdot\mathbf a=(-56\,\mathbf i)\cdot(14\,\mathbf i)=(-56)(14)=-784$

Next,

$\mathbf a+\mathbf b=(14\,\mathbf i)+(-4\,\mathbf i+8\,\mathbf j)=10\,\mathbf i+8\,\mathbf j$

Then

$(\mathbf a+\mathbf b)\times\mathbf b=\begin{vmatrix}\mathbf i&\mathbf j&\mathbf k\\10&8&0\\-4&8&0\end{vmatrix}=112\,\mathbf k$

$((\mathbf a+\mathbf b)\times\mathbf b)\times\mathbf k=\begin{vmatrix}\mathbf i&\mathbf j&\mathbf k\\0&0&112\\0&0&1\end{vmatrix}=\mathbf 0$

4 0

4 years ago

en un maratòn participan corredores de todos los continentes 5/6 de los corredores son europeos se sabe que los americanos son l

Marysya12 [62]

Usando proporciones, se encuentra que 400 africanos han participado.

En total, hay x participantes.

$\frac{5}{6}$ de los corredores son europeos, o sea:

$E = \frac{5x}{6}$

Los americanos son la dècime parte de los europeos, o sea:

$Am = \frac{1}{10}E = \frac{5x}{60} = \frac{x}{12}$

Los africanos son la quinta parte de los americanos, o sea:

$Afr = \frac{1}{5}Am = \frac{x}{60}$

En la carrera han inscritos 24 000 participantes, o sea, $x = 24000$ . Por eso, la cantidad de africanos es:

$Afr = \frac{x}{60} = \frac{24000}{60} = 400$

Para obtener más información sobre las proporciones, puedes visitar a brainly.com/question/24615636

8 0

2 years ago

When reading a book, Charlie made a list by writing down the page number of the last page he finished reading at the end of each

Assoli18 [71]

Answer:

No. of pages he read by the end of the 8th day = 425

Step-by-step explanation:

Charlie started from page 1 and read the same number of pages each day. Suppose x is the number of pages he read each day, the last page he read on the first day would be:

This would be the first number he noted on the list.

The second page number can be determined by adding the number of pages he read to the last page for day 1.

Last page for day 2 = 1 + x + x

= 1 + 2x

Similarly, the last page he read on the third day is:

Last page for day 3 = 1 + 3x. Similarly,

Last page for day 4 = 1 + 4x

Last page for day 5 = 1 + 5x

Last page for day 6 = 1 + 6x

Last page for day 7 = 1 + 7x

Last page for day 8 = 1 + 8x

His Mom added all of the page numbers and got a total of 432. So,

432 = 1+x + 1+2x + 1+3x + 1+4x + 1+5x + 1+6x + 1+7x + 1+8x

432 = 8 + 8x

8x = 432-8

8x = 424

x = 424/8

x = 53

By the end of the 8th day he actually read 1 + 8x pages. Substituting the value of x in this expression, we get:

No. of pages he read by the end of the 8th day = 1 + 8(53)

= 1 + 424

No. of pages he read by the end of the 8th day = 425

4 0

4 years ago

15 POINTS WILL GIVE BRAINLIEST

11Alexandr11 [23.1K]

Answer:

[27,3) i think

Step-by-step explanation:

5 0

3 years ago

Solve the system of equations.<br> - 3x + 2y = 56<br> - 5 - 2y = 24

Oduvanchick [21]

Awnser

y=13

Step-by-step explanation:

-3x+2y=56

-5x-2y=24

so first we want to get rid of one variable, in this example we dont need to multiply because the y's cancel out

so we have

-8x=80

x=-10

now plug in x into an original equation

-3(-10)+2y=56

2y=26

y=13

hope that helps

4 0

3 years ago

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