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2 years ago

PLZ IM BEGGING YOU

Mathematics

1 answer:

antoniya [11.8K]2 years ago

5 0

Answer:

200

Step-by-step explanation:

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The radius of a cone is increasing at a constant rate of 7 meters per minute, and the volume is decreasing at a rate of 236 cubi

storchak [24]

Answer:

The rate of change of the height is 0.021 meters per minute

Step-by-step explanation:

From the formula

$V = \frac{1}{3}\pi r^{2}h$

Differentiate the equation with respect to time t, such that

$\frac{d}{dt} (V) = \frac{d}{dt} (\frac{1}{3}\pi r^{2}h)$

$\frac{dV}{dt} = \frac{1}{3}\pi \frac{d}{dt} (r^{2}h)$

To differentiate the product,

Let r² = u, so that

$\frac{dV}{dt} = \frac{1}{3}\pi \frac{d}{dt} (uh)$

Then, using product rule

$\frac{dV}{dt} = \frac{1}{3}\pi [u\frac{dh}{dt} + h\frac{du}{dt}]$

Since $u = r^{2}$

Then, $\frac{du}{dr} = 2r$

Using the Chain's rule

$\frac{du}{dt} = \frac{du}{dr} \times \frac{dr}{dt}$

∴ $\frac{dV}{dt} = \frac{1}{3}\pi [u\frac{dh}{dt} + h(\frac{du}{dr} \times \frac{dr}{dt})]$

Then,

$\frac{dV}{dt} = \frac{1}{3}\pi [r^{2} \frac{dh}{dt} + h(2r) \frac{dr}{dt}]$

Now,

From the question

$\frac{dr}{dt} = 7 m/min$

$\frac{dV}{dt} = 236 m^{3}/min$

At the instant when $r = 99 m$

and $V = 180 m^{3}$

We will determine the value of h, using

$V = \frac{1}{3}\pi r^{2}h$

$180 = \frac{1}{3}\pi (99)^{2}h$

$180 \times 3 = 9801\pi h$

$h =\frac{540}{9801\pi }$

$h =\frac{20}{363\pi }$

Now, Putting the parameters into the equation

$\frac{dV}{dt} = \frac{1}{3}\pi [r^{2} \frac{dh}{dt} + h(2r) \frac{dr}{dt}]$

$236 = \frac{1}{3}\pi [(99)^{2} \frac{dh}{dt} + (\frac{20}{363\pi }) (2(99)) (7)]$

$236 \times 3 = \pi [9801 \frac{dh}{dt} + (\frac{20}{363\pi }) 1386]$

$708 = 9801\pi \frac{dh}{dt} + \frac{27720}{363}$

$708 = 30790.75 \frac{dh}{dt} + 76.36$

$708 - 76.36 = 30790.75\frac{dh}{dt}$

$631.64 = 30790.75\frac{dh}{dt}$

$\frac{dh}{dt}= \frac{631.64}{30790.75}$

$\frac{dh}{dt} = 0.021 m/min$

Hence, the rate of change of the height is 0.021 meters per minute.

3 0

2 years ago

What are the two words that allow you to check your division problem backward?

Dahasolnce [82]

Answer:

inverse operation

Step-by-step explanation:

Inverse means opposite. The opposite of division is multiplication. For example, if you divided 15 by 3, the answer is 5. If you multiply 5 by 3, the answer is 15. You know your answer is correct by checking it with the inverse operation.

Hope this helps!! Have a wonderful day :3

3 0

3 years ago

What algebraic expression must be added to the sum of 3x2 +4x+8 and 2x2−6x+3 to give 9x2−2x−5 as the result?

vesna_86 [32]

Answer:

$4x^2-16$

Step-by-step explanation:

-This is an addition/subtraction problem.

#We subtract the sum of the first two expression from the third expression:

$\#Add \ first \ two\\\\=3x^2 +4x+8 +2x^2-6x+3\\\\=5x^2-2x+11\\\\\# Subtract\ from \ the \ third\\=(9x^2-2x-5)-(5x^2-2x+11)\\\\=9x^2-2x-5-5x^2+2x-11\\\\=4x^2-16$

Hence, the expression $4x^2-16$ must be added to the first two.

7 0

2 years ago

The amount 5th grade students grow during the school year is normally distributed with a mean of inches and a standard deviation

Andrej [43]

Answer: 475

Step-by-step explanation:

6 0

2 years ago

To rent a moving truck there is a fee of $150 and each mile you drive costs an extra $1.75 per mile, where R(x) is the total cos

abruzzese [7]

Answer:

$318

Step-by-step explanation:

First, we want to set up an equation to solve this problem by using the information given to us. We're asked for the total cost, so we want one side of the equation to be $R(x)=$ . Then, we know that the initial cost is $150, no matter how many miles we drive. We are also told that each mile is $1.75.

$R(x)=150+1.75x$

The problem tells us that we are driving 96 miles, so we can plug in 96 for $x$ and solve.

$R(x)=150+1.75(96)\\R(x)=150+168\\R(x)=318$

The total cost of the rental is going to $318.

Hope this helps!

8 0

2 years ago