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3 years ago

A manager must select 5 delivery locations from 9 that are available. Find the number of

Mathematics

1 answer:

Dmitry_Shevchenko [17]3 years ago

6 0

$C^9_5=\dfrac{9!}{5!4!}=\dfrac{6\cdot7\cdot8\cdot9}{2\cdot3\cdot4}=2\cdot7\cdot9=126$

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Evaluate the integral by making an appropriate change of variables.

VARVARA [1.3K]

By inspecting the integrand, the "obvious" choice for substitution would be

u = y + x

v = y - x

Solving for x and y, we would have

x = (u - v)/2

y = (u + v)/2

in which case the Jacobian and its determinant are

$J=\begin{bmatrix}x_u&x_v\\y_u&y_v\end{bmatrix}=\dfrac12\begin{bmatrix}1&-1\\1&1\end{bmatrix}\implies|\det J|=\left|\dfrac12\right|=\dfrac12$

The trapezoid R has two of its edges on the lines x + y = 8 and x + y = 9, so right away, we have 8 ≤ u ≤ 9.

Then for v, we observe that when x = 0 (the lowest edge of R), v = y ; similarly, when y = 0 (the leftmost edge of R), v = -x. So

-x ≤ v ≤ y

-(u - v)/2 ≤ v ≤ (u + v)/2

-u + v ≤ 2v ≤ u + v

-u ≤ v ≤ u

So, the integral becomes

$\displaystyle\iint_R5\cos\left(7\frac{y-x}{y+x}\right)\,\mathrm dA=\int_8^9\int_{-u}^u\frac52\cos\left(\frac{7v}u\right)\,\mathrm dv\,\mathrm du$

$=\displaystyle\frac52\int_8^9\frac u7(\sin7-\sin(-7))\,\mathrm du$

$=\displaystyle\frac57\sin7\int_8^9u\,\mathrm du$

$=\displaystyle\frac5{14}\sin7(9^2-8^2)=\boxed{\frac{85}{14}\sin7}$

4 0

3 years ago

A rectangular prism is 7 centimeters long, 5 centimeters wide, and 4 centimeters tall. Which values are the areas of cross secti

VladimirAG [237]

Cross section is the area you make when you make a cut across a shape. In this case, the cut must be parallel to the base. Hence, the cut shape would be same to that of the base. The base's dimensions are 7 cm long x 5 cm wide. Thus, the cross section area is 35 square centimeters.

3 0

3 years ago

Read 2 more answers

Can someone help with this please?

ipn [44]

$7^2=7\cdot7=49\\\\8^2=8\cdot8=64\\\\\sqrt{49}$

3 0

3 years ago

Read 2 more answers

Find the quotient of -85^2-27n+76 / -17n-19

bagirrra123 [75]

Answer:
5n-4

Explanation:
The given expression is:
$\frac{-85n^2-27n+76}{-17n-19}$

1- Take the negative as a common factor from both the numerator and the denominator. This will give us:
$\frac{-(85n^2+27n-76)}{-(17n+19)}$

2- Cancel out the negative sign (common factor) from the numerator and denominator. This will give us:
$\frac{(85n^2+27n-76)}{(17n+19)}$

3- Factor the numerator. This wil give:
$\frac{(5n-4)(17n+19)}{(17n+19)}$

4- Finally, cancel out the (17n+19) which common in both numerator and denominator. This will give us the final expression:
5n-4

Hope this helps :)

6 0

3 years ago

The chef took out 54.8 g of butter but then found out that he took out 6.9 g of butter more than he needed. How much butter did

stira [4]

Answer:

47.9 gm

Step-by-step explanation:

According to the scenario, calculation of the given data are as follows,

Total butter took = 54.8 gm

Extra butter quantity = 6.9g

So, we can calculate the exact quantity of butter needed by using following formula,

Exact butter needed = Total butter - Extra butter quantity

By putting the value, we get

Exact butter needed = 54.8 gm - 6.9gm

= 47.9 gm

Hence, he need 47.9gm butter.

6 0

3 years ago