Please someone help me! asap!!

Elina [12.6K]

D x= -9
Y=9
Because 4(-9)+45=9
I just put in each one and d got it right.

5 0

3 years ago

Mai wants to make an open top box by cutting out corners of a square piece of cardboard and folding up the sides. The cardboard

Bumek [7]

Answer:

$V(x)=(4x^{3}-40x^{2}+100x)\ cm^3$

The domain for x is all real numbers greater than zero and less than 5 com

Step-by-step explanation:

<em><u>The question is</u></em>

What is the volume of the open top box as a function of the side length x in cm of the square cutouts?

see the attached figure to better understand the problem

Let

x -----> the side length in cm of the square cutouts

we know that

The volume of the open top box is

$V=LWH$

we have

$L=(10-2x)\ cm$

$W=(10-2x)\ cm$

$H=x)\ cm$

substitute

$V(x)=(10-2x)(10-2x)x\\\\V(x)=(100-40x+4x^{2})x\\\\V(x)=(4x^{3}-40x^{2}+100x)\ cm^3$

Find the domain for x

we know that

$(10-2x) > 0\\10> 2x\\ 5 > x\\x < 5\ cm$

so

The domain is the interval (0,5)

The domain is all real numbers greater than zero and less than 5 cm

therefore

The volume of the open top box as a function of the side length x in cm of the square cutouts is

$V(x)=(4x^{3}-40x^{2}+100x)\ cm^3$

5 0

3 years ago

Every ninth person in line at a movie theater gets free popcorn. Every sixth person gets free apple juice. Shani says that the t

pishuonlain [190]

Find the common multiples:

Multiples of 6: 6, 12, 18, 24, 30, 36, 42, 48

Multiples of 9: 9, 18, 27, 36, 45

The common multiples are 18 and 36

The first person in line to get both free would be the 18th person and then the 36th person.

So she is correct that the 36th person would get both free, but they wouldn't be the first person to do it.

8 0

3 years ago

Jan spends part of her year as a member of a gym. She then finds a better deal at another gym, so she cancels her membership wit

valkas [14]

She spent 8 months in the 1st gym and 4 months in the 2nd gym

Step-by-step explanation:

Jan spends part of her year as a member of a gym.

She then finds a better deal at another gym so she cancels her membership with the first gym after x months
She spends the rest of the year, y months, with the second gym
The membership to the first gym costs $75 per month, while the membership for the second gym costs $45 per month
She ended up spending a total of $780 over the course of the year

We need to find how much time she spent at each gym

∵ She spent x months in the 1st gym

∵ She spent y months in the 2nd gym

∵ Her course is a year

- There are 12 months in a year

∴ x + y = 12 ⇒ (1)

∵ The membership to the first gym costs $75 per month

∵ The membership to the second gym costs $45 per month

∵ She ended up spending a total of $780 over the course

∴ 75x + 45y = 780 ⇒ (2)

Now we have a system of equations to solve it

Multiply equation (1) by -45 to eliminate y

∵ -45x - 45y = -540 ⇒ (3)

- Add equations (2) and (3)

∴ 30x = 240

- Divide both sides by 30

∴ x = 8

- Substitute the value of x in equation (1) to find y

∵ 8 + y = 12

- Subtract 8 from both sides

∴ y = 4

She spent 8 months in the 1st gym and 4 months in the 2nd gym

Learn more:

You can learn more about the system of equations in brainly.com/question/2115716

#LearnwithBrainly

4 0

3 years ago

A spherical balloon is inflating with helium at a rate of 64 pi StartFraction ft cubed Over min EndFraction . How fast is the b

olga2289 [7]

Answer:

The radius of the balloon is increasing at a rate of 4 feet per minute.

Step-by-step explanation:

We are given the following in the question:

$\dfrac{dV}{dt} = 64\pi \dfrac{\text{ ft}^3}{\text{min}}$

Volume of sphere is given by

$V = \dfrac{4}{3}\pi r^3$

where r is the radius of the balloon.

Instant radius, r = 2 ft

Rate of change of volume =

$\dfrac{dV}{dt} = \dfrac{d}{dt}(\dfrac{4}{3}\pi r^3)\\\\\dfrac{dV}{dt} =4\pi r^2\dfrac{dr}{dt}$

Putting values, we get,

$64\pi = 4\pi (2)^2\dfrac{dr}{dt}\\\\\Rightarrow \dfrac{dr}{dt} = 4$

Thus, the radius of the balloon is increasing at a rate of 4 feet per minute.

5 0

3 years ago