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3 years ago

The cone in the figure below has a volume of 72π cubic centimeters and a height of 6

Mathematics

1 answer:

AleksAgata [21]3 years ago

8 0

Answer:

6 cm

Step-by-step explanation:

The volume of a cone = (1/3) πr²h

72π = (1/3) π r² 6

72 = (1/3) r² 6

Divide both sides by 6

12 = (1/3) r²

Multiply both sides by 3

36 = r²

So r (radius) = 6 cm

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Can someone check whether its correct or no? this is supposed to be the steps in integration by parts

Gwar [14]

Answer:

$\displaystyle - \int \dfrac{\sin(2x)}{e^{2x}}\: \text{d}x=\dfrac{\sin(2x)}{4e^{2x}}+\dfrac{\cos(2x)}{4e^{2x}}+\text{C}$

Step-by-step explanation:

$\boxed{\begin{minipage}{5 cm}\underline{Integration by parts} \\\\$\displaystyle \int u \dfrac{\text{d}v}{\text{d}x}\:\text{d}x=uv-\int v\: \dfrac{\text{d}u}{\text{d}x}\:\text{d}x$ \\ \end{minipage}}$

Given integral:

$\displaystyle -\int \dfrac{\sin(2x)}{e^{2x}}\:\text{d}x$

$\textsf{Rewrite }\dfrac{1}{e^{2x}} \textsf{ as }e^{-2x} \textsf{ and bring the negative inside the integral}:$

$\implies \displaystyle \int -e^{-2x}\sin(2x)\:\text{d}x$

Using <u>integration by parts</u>:

$\textsf{Let }\:u=\sin (2x) \implies \dfrac{\text{d}u}{\text{d}x}=2 \cos (2x)$

$\textsf{Let }\:\dfrac{\text{d}v}{\text{d}x}=-e^{-2x} \implies v=\dfrac{1}{2}e^{-2x}$

Therefore:

$\begin{aligned}\implies \displaystyle -\int e^{-2x}\sin(2x)\:\text{d}x & =\dfrac{1}{2}e^{-2x}\sin (2x)- \int \dfrac{1}{2}e^{-2x} \cdot 2 \cos (2x)\:\text{d}x\\\\& =\dfrac{1}{2}e^{-2x}\sin (2x)- \int e^{-2x} \cos (2x)\:\text{d}x\end{aligned}$

$\displaystyle \textsf{For }\:-\int e^{-2x} \cos (2x)\:\text{d}x \quad \textsf{integrate by parts}:$

$\textsf{Let }\:u=\cos(2x) \implies \dfrac{\text{d}u}{\text{d}x}=-2 \sin(2x)$

$\textsf{Let }\:\dfrac{\text{d}v}{\text{d}x}=-e^{-2x} \implies v=\dfrac{1}{2}e^{-2x}$

$\begin{aligned}\implies \displaystyle -\int e^{-2x}\cos(2x)\:\text{d}x & =\dfrac{1}{2}e^{-2x}\cos(2x)- \int \dfrac{1}{2}e^{-2x} \cdot -2 \sin(2x)\:\text{d}x\\\\& =\dfrac{1}{2}e^{-2x}\cos(2x)+ \int e^{-2x} \sin(2x)\:\text{d}x\end{aligned}$

Therefore:

$\implies \displaystyle -\int e^{-2x}\sin(2x)\:\text{d}x =\dfrac{1}{2}e^{-2x}\sin (2x) +\dfrac{1}{2}e^{-2x}\cos(2x)+ \int e^{-2x} \sin(2x)\:\text{d}x$

$\textsf{Subtract }\: \displaystyle \int e^{-2x}\sin(2x)\:\text{d}x \quad \textsf{from both sides and add the constant C}:$

$\implies \displaystyle -2\int e^{-2x}\sin(2x)\:\text{d}x =\dfrac{1}{2}e^{-2x}\sin (2x) +\dfrac{1}{2}e^{-2x}\cos(2x)+\text{C}$

Divide both sides by 2:

$\implies \displaystyle -\int e^{-2x}\sin(2x)\:\text{d}x =\dfrac{1}{4}e^{-2x}\sin (2x) +\dfrac{1}{4}e^{-2x}\cos(2x)+\text{C}$

Rewrite in the same format as the given integral:

$\displaystyle \implies - \int \dfrac{\sin(2x)}{e^{2x}}\: \text{d}x=\dfrac{\sin(2x)}{4e^{2x}}+\dfrac{\cos(2x)}{4e^{2x}}+\text{C}$

5 0

2 years ago

What is 4/8 divided by 7/8

kifflom [539]

Answer: 4/7

Step-by-step explanation:

4/8 / 4/7

now you do multilpication so,

4x8

over

8x7

32/56 divided by 56/8=

4/7

hope i helped <33

8 0

3 years ago

Read 2 more answers

Don’t put no links just put a answer now can someone help me

Harlamova29_29 [7]

Nooooooooooooooooooooooooo

4 0

2 years ago

In a certain clinical study, 15% of participants were classified as heavy smokers, 25% as light-smokers, and the rest as non-smo

Natasha_Volkova [10]

Answer:

There is a 28.57% probability that a randomly selected participant who died by the end of the study was a non-smoker.

Step-by-step explanation:

We have the following probabilities:

A 15% probability that a participant is classified as a heavy smoker.

A 25% probability that a participant is classified as a light smoker.

A 100% - 25% - 15% = 60% probability that a participant is classified as a non smoker.

A x% probability that a non smoker dies.

A 3x% probability that a light smoker dies.

A 5x% probability that a heavy smoker dies.

This can be formulated as the following problem:

What is the probability of B happening, knowing that A has happened.

It can be calculated by the following formula

$P = \frac{P(B).P(A/B)}{P(A)}$

Where P(B) is the probability of B happening, P(A/B) is the probability of A happening knowing that B happened and P(A) is the probability of A happening.

This problem is:

What is the probability of the participant being a non-smoker, given that he died?

P(B) is the probability that the participant is a non smoker. So

$P(B) = 0.6$

P(A/B) is the probability that the participant dies, given that he is a non smoker. So:

$P(A/B) = x$

P(A) is the probability that the participant dies:

$P(A) = P_{1} + P_{2} + P_{3}$

$P_{1}$ is the probability that a heavy smoker is selected and that he dies. So:

$P_{1} = 0.15*5x = 0.75x$

$P_{2}$ is the probability that a light smoker is selected and that he dies. So:

$P_{2} = 0.25*3x = 0.75x$

$P_{3}$ is the probability that a non-smoker is selected and that he dies. So:

$P_{3} = 0.60*x = 0.60x$

The probability that a participant dies is:

$P(A) = P_{1} + P_{2} + P_{3} = 0.75x + 0.75x + 0.60x = 2.10x$

The probability of the participant being a non-smoker, given that he died, is:

$P = \frac{P(B).P(A/B)}{P(A)} = \frac{0.6x}{2.10x} = \frac{0.6}{2.10} = 0.2857$

There is a 28.57% probability that a randomly selected participant who died by the end of the study was a non-smoker.

7 0

3 years ago

PLZ HEEEELP!!!!! 10 POINTS!!!!

katrin2010 [14]

Answer:

Step-by-step explanation:

Part a

We need two inequalities, one for time worked at each job and the other

for amounts of money earned.

time: Let b and c represent the time (number of hours) worked at babysitting and landscaping respectively. Then b + c ≤ 20 hrs/wk

earnings: Let ($3/hr)(b) represents the amount of money earned babysitting for b hour. Let ($7/hr)(c) represent the money earned working at landscaping. These amounts are <em>per week</em>. The appropriate inequality is ($3/hr)(b) + ($7/hr)(c) ≥ $84 per week. The other inequality is

b + c ≤ 20 hrs/wk.

Part b:

As before, b + c ≤ 20 hrs/wk. What happens if Chet spends all his 20 hours babysitting? To answer this, set c = 0 (no landscaping hours). Then b ≤ 20 hours. At $3/hr, he could earn only $60 and have no time left for landscaping. Not good.

Let's experiment: suppose he works 15 hours babysitting and 5 hours landscaping. His earnings would be $45 + $35, or $80. Still not enough; he wants to earn $84 total. Let's redistribute his time and try again: suppose he works 14 hours babysitting and 6 hours landscaping; his earnings would be $42 + $42, or $84. So {b = 14 hours and c + 6 hours} is a solution. As we continue to reduce the number of hours Chet works babysitting and correspondingly increase those he works landscaping, his earnings will go up, beyond $84.

Here's a table that summarizes this:

babysitting landscaping total amount

hours hours earned

15 5 $60 (not acceptable)

14 6 $84 (borderline acceptable)

12 8 $36 + $42 = $78 (great)

6 14 $116 (greater still)

2 18 $132

1 19 $134

0 20 $140

Summary: Chet can work anywhere from 0 to 14 hours babysitting and expect to earn $84 or more.

4 0

2 years ago