Recent content by magicarpet512

  1. M

    Probability P(A\B) = P(A) - P(B)

    Yes, thank you. I've tried that... unless I'm missing something? A as the union of disjoint sets is A = (A \cap B) \cup (A \cap B^{c}). So, P(A) = P((A \cap B) + (A \cap B^{c}). When i plug this in and do some rearranging, i just get right back to where i ended up in the original post?
  2. M

    Probability P(A\B) = P(A) - P(B)

    Homework Statement Let A \subseteq B \subseteq S where S is a sample space. Show that P(A \setminus B) = P(A) - P(B) Homework Equations A \setminus B denotes set difference; these are probability functions. The Attempt at a Solution I have, P(A \setminus B) = P(A \cap B^{C})...
  3. M

    Basic Lin Alg - Angle Between Vectors

    sorry, i didnt mean to say that! As spamiam is hinting, how do you get \theta?
  4. M

    Basic Lin Alg - Angle Between Vectors

    Your <u,v> must be a vector, not a scaler.
  5. M

    Unique soution of this 2nd order diff equation.

    Anyways, it looks like you've got a simple homogeneous equation here: y'' = 2y' + 4y in which the 1st thing you need to do is find the eigenvalues.
  6. M

    Unique soution of this 2nd order diff equation.

    Is this the variable x or 2 times y'(x)?
  7. M

    Comparing the Difficulty of Undergraduate and Graduate Economics Programs

    And here is a very interesting article to wrap up The Great Debate of twofish and shackelford! Written by the 2008 Nobel Prize for Economics winner Paul Krugman. It really puts into perspective the history of clashes between Austrian & Keynesian economics. I think twofish would side with this...
  8. M

    Solving the Limit of a[n] as n Goes to Infinity

    I think we can find the sum of a series only if it is a geometric series or a telescoping sum, and from a quick glance this doesn't look like either one. Otherwise we would need some math software to approximate the sum.
  9. M

    For the webpage title: Proving the Oddness of 5x-3 for Even x Using Direct Proof

    I should of thought about this earlier, but to some people might not think that "by substitution property of equality" makes sense. The grader might count off and say "by substitution and equality of what?" I'm sure you will come across some kind of Uniqueness & Existence theorem one of...
  10. M

    For the webpage title: Proving the Oddness of 5x-3 for Even x Using Direct Proof

    TylerH: In your intro to proofs class you will quite often find yourself being pretty wordy in your proofs by using phrases such as " by substitution property of equality, it follows that." This is perfectly fine, and I would encourage you to be wordy like this, it will help you see what needs...
  11. M

    Equation for line connecting 2 planes

    For the second part of the question (equation of line from the intersection of the planes), take the cross product of the normal vector from the 1st and 2nd planes (this will give you a new normal vector that is perpendicular to the normal vectors of the two planes, or in other words this new...
  12. M

    Equation for line connecting 2 planes

    What do you need to come up with an equation of a line? You need a point and a slope. A point P is given in the problem, and you can think of your normal vector as a slope. Now its just a matter of putting these things together in a multivariable point slope formula to get the equation of a plane.
  13. M

    Why is the vector field tangent to the surface?

    z is defined as a function of x and y here. Why or how are you thinking that it is something different?
  14. M

    For the webpage title: Proving the Oddness of 5x-3 for Even x Using Direct Proof

    Are these always necessary at the end of a proof? I hardly ever use these on homeworks or exams, unless I have more than one proof on one page. But of course i see the importance of using these in a more formal setting like writing a paper.
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