help on the following problems

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happyman

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Sep 18, 2008
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Your Question
I need help on the following calculus problems?
It would be greatly appreciated if you could show all work:

For problems 1-3 write an integral for the area, and calculate the area by the fundamental theorem

1) Bounded by the graphs of y=((0.2x)^2)+3 and y=(x^2)-4x+3
2) Bounded by the graphs of y=((secx)^2) and y= (e^2x)
3) Bounded by the graphs of y= x+3 and x= (-y^2)+6y-7

Problem #4: The parabola y=9-(x^2) is rotated about the y-axis to form a paraboloid. A cylinder is coaxially inscribed in the paraboloid.

a) find the radius and altitude of maximum volume

b) find the radius and altitude of the cylinder of maximum total area

c) find the radius and altitude of the cylinder of maximum total aarea

d) does the maximum-volume cylinder have same dimensions as either of the maximum-area cylinders in 4b or c?

e) if the cylinder of maximum volume is inscribed in the paraboloid formed by rotating the parabole y- a^2-x^2 about the y-axis, does the ratio (cylinder radius):(paraboloid radius) depend in any way on how long the paraboloid is?

Problem #5: Phoebe is returning to earth in her spaceship when she detects an oxygen tank leak. She knows that the rate of change of pressure is directly proportional to the pressure of the remaining oxygen.

a) write a differential equation that expresses this fact and solve it subject to the initial conidtion that pressure is 3000 psi at time t=0 when Phoebe discovers the leak.

b) Five hours after she discovers the leak, the pressure has dropped to 2300 psi. At that time, Phoebe is still 20hr away from the earth. Will she make it home before the pressure drops to 800 psi?
 
i was wondering if you could solve the problems for me, I'm actually a teacher at a local high school and I'm creating a test for a class, but a huge family crisis is going on and I would usually have the time to create an answer key for the test but right now I don't, so I was wondering if you could help out, if you can't its ok, I can try to stay up until 4am and create the answer key myself and then head over to work at 6am
 
happyman said:
Your Question
I need help on the following calculus problems?
It would be greatly appreciated if you could show all work:

For problems 1-3 write an integral for the area, and calculate the area by the fundamental theorem

1) Bounded by the graphs of y=((0.2x)^2)+3 and y=(x^2)-4x+3
2) Bounded by the graphs of y=((secx)^2) and y= (e^2x)
3) Bounded by the graphs of y= x+3 and x= (-y^2)+6y-7

Problem #4: The parabola y=9-(x^2) is rotated about the y-axis to form a paraboloid. A cylinder is coaxially inscribed in the paraboloid.

a) find the radius and altitude of maximum volume

b) find the radius and altitude of the cylinder of maximum total area

c) find the radius and altitude of the cylinder of maximum total aarea

d) does the maximum-volume cylinder have same dimensions as either of the maximum-area cylinders in 4b or c?

e) if the cylinder of maximum volume is inscribed in the paraboloid formed by rotating the parabole y- a^2-x^2 about the y-axis, does the ratio (cylinder radius):(paraboloid radius) depend in any way on how long the paraboloid is?

Problem #5: Phoebe is returning to earth in her spaceship when she detects an oxygen tank leak. She knows that the rate of change of pressure is directly proportional to the pressure of the remaining oxygen.

a) write a differential equation that expresses this fact and solve it subject to the initial conidtion that pressure is 3000 psi at time t=0 when Phoebe discovers the leak.

b) Five hours after she discovers the leak, the pressure has dropped to 2300 psi. At that time, Phoebe is still 20hr away from the earth. Will she make it home before the pressure drops to 800 psi?
Click to expand...

You posted 7 sets problems prior to this without showing any work. You have been told to show your work all the prior times - but it seems your skill of reading/comprehension leaves you at the most inopportune time - and you have no response.
 
happyman said:
... I can try to stay up until 4am and create the answer key myself and then head over to work at 6am
Click to expand...


There you go! That's a good plan.

(I wish you good fortune.)

 
Since September 17 you have been posting - not a single line of work. Several times you claimed you are lost - now you are claiming you are a teacher. Now I am lost......
 
ok i am sorry I was just asking for some help, I am going through a lot of trouble with my family and was just looking for some help
 
mmm4444bot said:
happyman said:
... I can try to stay up until 4am and create the answer key myself and then head over to work at 6am
Click to expand...


There you go! That's a good plan.

(I wish you good fortune.)
Click to expand...

And I wish your students good fortune as well.

Here's another possibility for what you could do: If you are a qualified teacher, get some sleep for your own mental health, and just turn it into a learning discussion for the students in your class. They know you and are more likely to understand your family issues than people on an anonymous math help board. These are some very tough problems, and we all have jobs of our own as well. Yes, some of us work with kids in the public schools, but not all of us. You could show up and take a day or two to go over the problems, asking kids to grade their own test and getting them engaged in the discussion.

If you have to use a sub because of other problems, it would be better to get some sleep anyway. The sub won't be able to handle these problems. I think it would be better for your kids for you to get back into the class and take them through the solution process for these problems that look pretty good to me. They might actually learn something by listening to how other kids worked through the problems.

-Paul
 
I am dissapointed that you are not willing to help, but your advice is taken
 
happyman said:
I am dissapointed that you are not willing to help
Click to expand...
You've been helped repeatedly over the last few months. But we can't teach your class for you.

From what you have posted, you perhaps need to return to your area of expertise, and allow the district to hire a replacement who is familiar with middle- or even high-school math. As any reasonable educator would of course understand, attempting to teach students third-hand through somebody who is not familiar with the material anyway has almost zero chance of success. And we wouldn't dream of harming your students that way.

Eliz.
 
I am a teacher also, and I feel sympathetic to your needs. Here are the first three:

For problems 1-3 write an integral for the area, and calculate the area by the fundamental theorem

1) Bounded by the graphs of y=((0.2x)^2)+3 and y=x^2-4x+3
int [(0.2x)^2+3 - (x^2-4x+3)] dx from x = 0 to x = 25/6

2) Bounded by the graphs of y=sec^2 x and y= e^(2x)
int [e^(2x) - sec^2 x] dx from x = 0 to x = 1.292...

3) Bounded by the graphs of y= x+3 and x= -y^2+6y-7
int [(-y^2+6y-7) - (y - 3)] dy from y = 0.9 to y = 3.9
You need to solve the system algebraically to find the actual intersection points.

It looks like you need to review calculus concepts.
 
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