Recent content by Juwane

  1. J

    Alternative formula for the Rule of Addition not working for some problems

    I did see your post. That's why I said, "But consider this example". Anyway, when the probabilities are independent, we don't need the minus part of the formula. This is enough: P( A \cup B) = P(A) + P(B) Then what is the use of writing the formula in the alternate form?
  2. J

    Alternative formula for the Rule of Addition not working for some problems

    But consider this example: A shopper goes to a fruit store. The probability that he will buy (1) bananas is 0.40, (2) oranges is 0.30, and (3) both bananas and oranges is 0.2. What is the probability that the shopper will buy bananas, oranges, or both? Using the usual formula: P( B...
  3. J

    Alternative formula for the Rule of Addition not working for some problems

    In probability, the rule of addition is: P( A \cup B) = P(A) + P(B) - P(A \cap B) This can be written as P( A \cup B) = P(A) + P(B) - P(A)P(B) However, I've seen that using both formulas for the same problem gives different answers in some problems. Does anyone know why? Is there a...
  4. J

    What's the formula for adding two complex numbers in polar form?

    I've used a search engine many times before I posted this question here. I couldn't find anything. I've a faint idea that the formula has to do with parallelogram law. However, I need a formula for adding two complex numbers in polar form, so the vectors have to be in polar form as well...
  5. J

    What's the formula for adding two complex numbers in polar form?

    I CAN'T. I've tried, but I can't really. Also, I have to use it in an exam tomorrow, and I've got other stuff to study, and I don't have time to figure it out. Please.
  6. J

    What's the formula for adding two complex numbers in polar form?

    Maybe, but I need the final, ready-made form of the formula.
  7. J

    What's the formula for adding two complex numbers in polar form?

    I really, really need to know the formula that adds (or subtracts) two complex numbers in polar form, and NOT in rectangular form. I know there is such formula (I saw it in some book), and it's composed of cosines and sines. Please, please don't tell me to convert back to rectangular form...
  8. J

    Will current take the path of least impedance in this circuit?

    Homework Statement See the circuit in the attached image. Homework Equations N/A Consider the circuit given in the attached image, then please answer the following questions: 1. When the current will come out of the current source, will all that current will go through the path...
  9. J

    Complex analysis: Find a function that maps z1 and z2 onto w1 and w2

    Yes, you're right. w2 is 1, not 3. I'll try to use the method you've given here. Thanks.
  10. J

    Complex analysis: Find a function that maps z1 and z2 onto w1 and w2

    Homework Statement What is the function (linear transformation) that maps z_{1} = 2 and z_{2} = -3i onto w_{1} = 1+i and w_{2} = 3? I think it's asking for the function that if you put 2 in it, it should give 1+i, and if you put -3i in the same function, it should give 3. The answer...
  11. J

    Engineering Find the voltage across a resistor in a difficult circuit

    Homework Statement Find the voltage across R1 (see attached image). Note that all values are known. Homework Equations Voltager divider might be used. I hope KVL doesn't have to be used here. The Attempt at a Solution My problem is that I don't know if the current from I1 is...
  12. J

    How to use the graph of the distance between any two points

    I used a graphing software to create the graph, and then I zoomed in many times on the part of the graph where d was the smallest. I used http://www.walterzorn.com/grapher/grapher_app.htm".
  13. J

    How to use the graph of the distance between any two points

    d is smallest when x is approx equal to 1.35296 The answer is correct as given at the back of the book. Yes, I didn't want to use derivatives for this question; but if I were to use derivatives, I would have differentiated the function and equated it to zero, and then would've solved for...
  14. J

    How to use the graph of the distance between any two points

    Homework Statement Write an expression for the distance between the point P(1,2) and an arbitrary point ( x, \sqrt{x} ) on the curve y = \sqrt{x}. Graph this distance versus x, and use the graph to find the x-coordinate of the point on the curve that is closest to the point P. Homework...
  15. J

    How can we know how many solutions an equation has?

    I understand that a quadratic function intersects the x-axis at most twice, but what the denominator of \frac{-3x^2 + 10x + 11}{x^2+3}? Surely that denominator changes the degree of the equation and hence the number of solutions?
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