I need your help on math...
Asked by
dina_didi (
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)
September 13th, 2014
I am trying to solve these questions but I can’t. I have to find the answers until tommorow. Do you know how to solve it? Any help will be appreciated!
1. Find the smallest distance between the start of the pivots and the surface. z=xy+5.
(As a note there is written √(x*x)(y*y)(z*z) )
2. Find this area on the surface 2x+3y+z-11=0 which minimizes the quantity Q=4*(x*x)(y*y)(z*z)
(There is a note <Langrad>)
3. Find the mass which is under the surface z=1/(y+2) and over the surface bounded by the curves y=x and (y*y)+x=2
4. Find the integral ∫∫∫vV dt
on (x*x)+(y*y)<=4
0<=z<=5
where V=((x*x)+(y*y))^(½)) * (x*Ix+y*Iy)
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7 Answers
Gosh, sure likes homework to me. I stopped doing other people’s homework when I was about 12.
@dina_didi, could you please clarify. I used to do this stuff but it’s been quite a while! This is not the best site for help with math homework lol.
1.
a. What do you mean “start of the pivots?” There must be more to the problem?
b. Re note: distance formula in 3 dimensions d=√(x2+y2+z^2)—an extension of Pythagoras
c. Is there any significance to the underline below (y*y) ?
2.
a. What do you mean “this area?”
b. 2x+3y+z=10 is a plane
c. <Langrad> Could it be Lagrangian?
3.
a. Find the mass: Do you mean volume?
b. Volume found w/ triple integral like problem 4
4.
a. What do symbols “lx” and “ly” mean?
b. Boundaries are that of a cylinder
@gasman sorry about the mistakes, English is not my native language… Thank you very much for your help!
1.a. “the beginning of the pivots”
c. actually I tried to erase that but I couldn’t.
2.a. The question requests for the place of the surface described from the equation to be found
b. what do you mean by saying it is a plane?
c. I made a typo, it is written as Lagrad. I am not sure if this is correct…
3.a. You are right
4. a. There is no explanation for this. The first is an i with a small x next to it and the second is an i with a small y.
Thanks again for your help! I am only asking because I couldn’t find the answers and I need to pass this exam (unfortunatelly our teacher was not the greatest and was constantly absent, so we have no idea how to deal with this exam)...
@dina_didi Ordinarily i (lower case) signals the use of complex numbers, though whether this is the case should be clear from the mathematical context. The general equation of a plane is ax+by+cz+d=0 where it’s tilted at some angle to each axis.
This is fairly advanced calculus with possibly some complex analysis thrown in. Have you understood previous lessons & been able to work most previous problems? I don’t see how you’re going to work problems if the meaning of the symbols is unclear. I’m afraid I can’t be of much help, since I’d have to review before working these out in detail. It shouldn’t be hard to find other sources of help, however. Good luck!
Thank you very much @gasman for your help! I solved some of these questions with your help and some help from a friend of mine and I hope for the best!
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