Recent content by larstuff

  1. L

    Help with Quiz Question on Graphs

    The function for the ellipse is: f(x)= 4/pi * sqrt ( 1 + ((x - 0,5)/0,5)^2 ) The TEX on these pages is difficult to get ... But again, though this is the correct function for the semi-ellipse between x=0 and x=1, with area exactly 1, you will get a hard time computing the arc length...
  2. L

    Help with Quiz Question on Graphs

    There seems to be a problem with the cut ellipsis too, I'm afraid. The equation for calculating arc length is given by the integral formula: So when trying to calculate this integral, we get similar problems to those of the rectangle. All ellipsis functions derived from simple...
  3. L

    The Probability of Getting At Least 3-of-a-Kind in a 3-Deck Card Game

    Yes, it does. There are 3x4 of each kind then in the three decks, that's to say 12 Fours, 12 Fives and so on. This is not a simple task, as far as I can see. Try to rule out the "oposite", that's to say, find the probability of getting only 1 of each kind + 1 or 2 of each kind + 2 of each kind...
  4. L

    Unable to calculate the Determinant of a large matrix

    That's not what I am getting here. I would have you start with the 1x1 matrix, find the det for that one, continue with the 2x2 matrix. Just use the simplest way of calculating the determinant (diagonal --> right --> down = + and diagonal --> left -->down = -).
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    How can I integrate by parts this one?

    This problem can not be solved because the function is not strictly converging towards infinity. You can calculate definite integrals, f.ex. [2,100 000], [2, 1 000 000] and so on, but there is no way this integral reaches a certain limit as x goes towards infinity. I agree with Random Variable...
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    Solve for the Area of a Region: Integral of sqrt(9-x^2) over [0,3]

    Try downloading the program Geogebra (Web Start) - it's free math software, then let it draw the graph of this "weird" thing. You'll probably see what the answer is..
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    The Probability of Getting At Least 3-of-a-Kind in a 3-Deck Card Game

    I'm not quite sure what the question is here. What does 3-of-a-kind mean in this situation? Does it mean 3 of the ace of Spades, 3 spades, 3 aces... In other words, precicely what is the outcome we seek to get? And - anyway, do not forget all possible combinations in your calculation.
  8. L

    Help with Quiz Question on Graphs

    Remember that Df for f(x) is [0,1]. So the sides are there, as given by condition 2), the latter part... :wink: But don't let's argue. I will give you right in the part of sides on a rectangle. Usually there are 4 of them..
  9. L

    Factorise p(x) as a product of linear factors

    Guesswork is a good thing in mathematics, but guesswork often need some kind of reasoning. Drawing a graph by hand / on computer is not guesswork in this case. You should come up with a more sophisticated way of showing what your guesswork builds on. One way to go by, is to look at the last...
  10. L

    Help with Quiz Question on Graphs

    No. Perhaps not, but what about the function f(x) = 8 ? Is that not a rectangle function on at clearly defined area, like this? So a rectangle, in this respect ,might be considered a function, howewer for this exercise, not the correct one, as f(x) needs to be 0 both at x=0 and x=1...
  11. L

    Volume of a spherical segment

    Le Cavalieris principle is about functions in the plane (2d) that are "hightened" into space (3d) by revolving them about the x-axis. A cut half circle would do here.
  12. L

    Help with Quiz Question on Graphs

    Triangle or trapezoid is simplest. I'm not sure if a rectangle would satisfy the conditions.
  13. L

    Unable to calculate the Determinant of a large matrix

    Try solving for the det. for matrixes from smaller to bigger. This will give an interesting result. Start with a 1x1 matrix, then a 2x2 matrix, and so on. A pattern will then emerge. The tricky part is to show why this pattern will continue. It all has to do with the diagonals - how many of...
  14. L

    Integration Problem: Solving 3/(1+4x)^0.5 from x=0 to x=2

    3/(1+4x)^0.5 = 3 * (1+4x)^(-0,5) Now you can use the common powers law with the exponent (-0,5). Adding 1 to this gives (0,5).
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    Unable to calculate the Determinant of a large matrix

    The determinant must eighter be 0 og -1. If the number of rows are even, then the determinant will be zero. If the number of rows are odd, the determinant will be -1.
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