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  1. H

    Combinatorics - can't really identify the problem

    If I read the problem correctly, you end up giving all 24 cans to the students. Why not just count the ways this can be done? first you must hand two cans to each, as they must receive at least two cans. Then figure out how to distribute the remaining 18 among three students. label them 1, 2...
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    Instantaneous rates of change. Exponential growth and Decay

    In your first equation, where did you get the 48 from? Maybe it should be 52. Then at t=4weeks, you would have t=4/52 years. I think your answer is in terms of years, not weeks. Same for the second equation. You converted 18 months into 1.5 years. The solution you have is in terms of grams...
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    Given a discontinuos function, show that it is not concave

    at this level of mathematics.. if you can even understand the question, you should get an "A".. :)
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    Given a discontinuos function, show that it is not concave

    so what you are trying to show is that if the function is not continuous, that it is convex?
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    Typical calculus qn. try to solve without calculus

    so, by the constraint you have two numbers which add up to twenty. Call one x, and the other 20-x. square both, and add. what do you know about a quadratic that gives a maximum or minimum?
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    Given a discontinuos function, show that it is not concave

    what kind of class is this problem from? A little context might help know where to go. I might be able to help you with showing a midpoint convex function is convex if it is continuous..
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    What am I overlooking? Vectors simple problem

    My first observation: You do not know the speed of the plane. If you assign a vector <1,1> here, you may be saying that the plane is traveling at sqrt(2) ground speed. adding the big vector, you can see you are actually reversing the direction of the plane. I think a good assumption would be...
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    There is something wrong with this vector problem

    The wind from the west is moving east. I think that is the problem here.. the east wind is contributing to the horizontal component you posted. In other words, I think you may want to try adding instead of subtracting.
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    There is something wrong with this vector problem

    what vectors did you add? You have to separate the original vector into horizontal and vertical components. then add the individual horizontal and vertical components. the wind form the west, does not add or subtract from the vertical component. A reasonable answer as to ground speed would...
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    Two-variable limit problem

    It is a lot easier to show the limit does not exist. All you have to do is find one path towards (0,0) that produces a limit that is not zero. Maybe you could try a quadratic, or a cubic..
  11. H

    How is equation transformed by matrix

    Or you could use the hint. You have an equation of a line. Find the coordinates for two points. If you have two coordinates, can you find the vector? Matrices transform vectors to vectors by multiplication.
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    How is equation transformed by matrix

    One way to try this problem would be to parametrize your line, and express it as a vector, then see how your matrix will map it.
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    Quick question on integral calculation

    Did you calculate the derivative?
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    Looking for old documents

    Anybody have anything?
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    Normal Distribution

    excuse lack of latex code here. from my general statistics book: 1. Yes, the mean of x(bar) is the population mean. 2. The standard deviation of the sample is sigma/sqrt(n). You need to calculate the z score of 610. Then use this with standard tables, or calculator to find P(.67<Z<Infinity).
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    Can mathematical logic fail?

    A few mathematicians tried to reduce math and reality itself to logic. Bertrand Russel comes to mind.. Now they call it naive set theory. If the barber of Seville is the only one to cut the beards of unshaven men of Seville who do not shave themselves. The barber is clean cut..
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    Need Some Advice

    I dunno. Maybe find a good local math friend? I took this as an independent study with two others. We helped each other..
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    Proving three 3D points are collinear with Cross Product

    mainly because if the points are co-linear, you have a parellpiped with volume zero..
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    E^x^2 integral

    I dunno. Maybe because all of the ordinary methods don't work.. maybe this will help.
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    Looking for old documents

    I'm looking for old lecture notes from Calculus classes in the 1920's and prior. Or lesson plans. Or anything to establish the identity of those enrolling in the courses then, or why they were taking the course.
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    Math Masters Program. Lots of questions. What to do?

    as far a "lucky" is concerned.. gawd almighty.. with the economy the way it is, an an older normally non-employable individual being offered this kind of opportunity.. well, what can I say.. I just hope I can "deliver".. I think I can..
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    Math Masters Program. Lots of questions. What to do?

    As far as teaching is concerned.. I have no problem helping those with algebra concepts as "rise over run" and such.. it was as hard for me then, as complex analaysis was last semester. I don't think I'll be dealing with epsilon-delta concepts with students, for at least a couple of years...
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    Math Masters Program. Lots of questions. What to do?

    As for myself, I've considered trying to sell Sierpinski Carpets, cheap.. Real low overhead.. :biggrin:
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    Math Masters Program. Lots of questions. What to do?

    Thanks for the "advice".. I think.. :biggrin: now for the important item, or items.. living on a stipend. "It's (almost) a living.." so what kind of scams am I to expect from fellow program participants? Will I find them pitching pennies on the local corner or something like that...
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    Math Masters Program. Lots of questions. What to do?

    I have been accepted into a graduate program at local university, along with being offered a teaching assistantship. Now comes the choice of what courses to choose. The master's program requires thirty credits of course work, along which includes introduction to real analysis, intro to...
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    Calculus for beginners

    I think almost anything you can find would help. I personally like something written in front of me. Almost anything published in the last fifty years won't exactly steer you in the wrong direction.. anything that deals with differential and integral calculus would probably help.. MIT...
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    Calculus for beginners

    The book name is worn off the cover.. on the title page it's just "Calculus". Looks like it really was published in U.S. New York John Wiley and Sons Inc Stewart's was really good though. This old book didn't go into a lot of explanation about the algebra involved. Forced me to go to other...
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    Calculus for beginners

    I first studied Calculus on my own from an old book from the book sale here.. it was published in something like 1927 or so. H.B. Phillips, PHD Published in London, wonder how it made it's way to the states.. 1927. The only difference between this and the class I later took.. they showed me...
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    Calculus for beginners

    I love the local friend of the library book sale. I have a library full of stuff from these sales from geometry to number theory, tensor analysis, advanced calculus, all kinds of stuff.. the advanced calculus book by Solkonikoff and the other by Apostel really helped prepare me for real...