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3 years ago

BRAINLIEST PLUS 22 POINTS

1 answer:

6 0

Hi there!

Angles that are complementary add up to 90. We know that in order to find the value of x, we'll need to create an equation. This equation would be (x + 15) + 48 = 90. This is because, together, the two angles must add up to 90.

ANSWER:
D - (x + 15) + 48 = 90

Hope this helps!! :)
If there's anything else that I can help you with, please let me know!

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Damien recently purchased a plot of land in the shape of a pentagon. He is planning to install a perimeter fence.

givi [52]

The answer is 6k^3+9k^2-15k+10

4 0

3 years ago

Aisha just received a paycheck from her new job she spends some of it buying music online and saves the rest in a bank account h

postnew [5]

Set y equal to 25 because this is the amount of money Aisha wants to save. This gives you 25 = 50-1.99x. Now we can solve for x, which is the variable. First, subtract 50 from both sides so that you can get the variable, x, by itself. After subtracting 50 from both sides, you are left with -25 = -1.99x . If it is easier for you, you can put the numbers on opposite sides so it reads -1.99x = -25 . Now divide both sides by -1.99 so that x is by itself. So -1.99x ÷-1.99 = 1x which is equal to just x and -25÷-1.99 = about 12.56, which is a decimal. (Remember that when you divide a negative number by a negative number, it becomes a positive number) Finally we have x = 12.56 (or 1x = 12.56) with 12.56 being equal to the number of songs Aisha can buy if she also wants to save money in her bank account. However, nobody can buy only .56 or part of a song. Round down to the nearest whole number, which is 12. This is how many songs she can buy and it makes sense because it is 12 entire songs, not 12 and just the chorus of a song. If you want to check, you can plug in 12 for x and she shouod have a little more than $25 in her bank account. So Aisha can buy 12 songs is she wants to save $25. I hope this helped :)

3 0

3 years ago

A metal cylinder can with an open top and closed bottom is to have volume 4 cubic feet. Approximate the dimensions that require

Aleksandr-060686 [28]

Answer:

$r\approx 1.084\ feet$

$h\approx 1.084\ feet$

$\displaystyle A=11.07\ ft^2$

Step-by-step explanation:

Optimizing With Derivatives

The procedure to optimize a function (find its maximum or minimum) consists in :

Produce a function which depends on only one variable
Compute the first derivative and set it equal to 0
Find the values for the variable, called critical points
Compute the second derivative
Evaluate the second derivative in the critical points. If it results positive, the critical point is a minimum, if it's negative, the critical point is a maximum

We know a cylinder has a volume of 4 $ft^3$ . The volume of a cylinder is given by

$\displaystyle V=\pi r^2h$

Equating it to 4

$\displaystyle \pi r^2h=4$

Let's solve for h

$\displaystyle h=\frac{4}{\pi r^2}$

A cylinder with an open-top has only one circle as the shape of the lid and has a lateral area computed as a rectangle of height h and base equal to the length of a circle. Thus, the total area of the material to make the cylinder is

$\displaystyle A=\pi r^2+2\pi rh$

Replacing the formula of h

$\displaystyle A=\pi r^2+2\pi r \left (\frac{4}{\pi r^2}\right )$

Simplifying

$\displaystyle A=\pi r^2+\frac{8}{r}$

We have the function of the area in terms of one variable. Now we compute the first derivative and equal it to zero

$\displaystyle A'=2\pi r-\frac{8}{r^2}=0$

Rearranging

$\displaystyle 2\pi r=\frac{8}{r^2}$

Solving for r

$\displaystyle r^3=\frac{4}{\pi }$

$\displaystyle r=\sqrt[3]{\frac{4}{\pi }}\approx 1.084\ feet$

Computing h

$\displaystyle h=\frac{4}{\pi \ r^2}\approx 1.084\ feet$

We can see the height and the radius are of the same size. We check if the critical point is a maximum or a minimum by computing the second derivative

$\displaystyle A''=2\pi+\frac{16}{r^3}$