1. A

    Difficult logarithm question - please help?

    If log[a]x=5 and log[a]y=8, solve: log[a]((ax^2)/(√y))^-2 --------- I am completely lost. Can someone please give me a step-by-step solution? Please and thank you!
  2. Vinod

    Normal distribution problem: wordings difficult to understand

    In a test of clerical ability which is distributed normally, a recruiting agency found that the mean and standard deviation for a group of fresh candidates were 60 and 10 respectively. For another experienced group, the mean and standard deviation were found to be 64 and 12. Assuming a cut-off...
  3. R

    Difficult wording for Quantifier - Logic

    I am really confused about this example from my textbook. Here it is: Suppose that we start with the universe that comprises only the 13 integers 2, 4, 6, 8,..., 24, 26. Then we can establish this statement: For all n (meaning n = 2, 4, 6,..., 26), we can write n as the sum of at most three...
  4. S

    Difficult integrals

    \int\frac{xsinx}{1+(cosx)^{2}}dx \int_{-\infty }^{\infty }e^{-x^{2}}dx \int\frac{\sqrt{\sqrt{x^4 + 1}-x^{2}}}{x^4 + 1}dx \int\frac{\sqrt{x}ln(x)e^{x}x^{3}}{\sqrt{lnx}}dx I have been working on these integral for 4 weeks... haven't been able to get anything yet. I am preparing for a competition...
  5. S

    What is the most difficult T series question?

    What is the most difficult telescoping series question? Can you please give me some?
  6. D

    Difficult variable to solve for. includes hyperbolic cos.

    I have the equation y = 1/k * ln(cosh(SQRT(g*k)*t)) My goal is to solve for k. This is for aerospace engineering and "k" includes a variable that I need. I have rearranged two ways already: 1) k = (acosh2(eyk))/(g*t2) 2) k = ln(cosh(SQRT(g*k)*t))/y I have NO IDEA as I am only a freshman...
  7. B

    Difficult anti differentiation question

    I have a curve, x^3 - 14x^2 + 59x -70 , and I need to run this line through it, mx - 70 , to make the area above the curve enclosed by the line equal to HALF of the area below the line enclosed by the curve..... So, I need to find the gradient (m) of the line to run through it for this to be...
  8. I

    Stats Inference w/ poisson and unbiased estimators. - finding difficult.

    Doing a variety of stats questions today, and don't know where to start with either of the parts... 1. The number of breakdowns per week for a type of computer is a random variable Y having a Poisson distribution with mean . A random sample Y1, Y2,...,Yn of observations on the weekly number of...
  9. NatalieSv94

    Positions of points in intersecting circles (DIFFICULT)

    Hi! here is the task I was talking about in my introductory thread I just posted a few minutes ago. I got this task yesterday and I have no idea how to even start with it. Here is an image of the task. I read it 100 times but I still don't know what to do! (Crying)
  10. NatalieSv94

    Positions of points in intersecting circles (DIFFICULT)

    The thread's moved Hi, I moved this thread since I though I uploaded it at the wrong place. So you can find it here instead: http://mathhelpforum.com/algebra/212436-positions-points-intersecting-circles-difficult.html#post767351 and pleeeeeeeeaaaaaaaaase heeeeeeeeeeeeeeeelp meeeeeeeeeeee! :P...
  11. G

    Can someone help me with the task.. very difficult

    Once the ground-workers made the concrete you took samples as the concrete was poured into the foundations. These samples were taken to the laboratory and after seven days the results returned were as follows: Ultimate Strength of Concrete Cubes (N/mm²) 15, 15, 10, 11, 20, 20, 11, 12, 18, 18...
  12. N

    Challenging problem!!!!!!! Really difficult

    A person is trapped in a dark cave with three ways out. One of them leads to safety after 2 hours of travel while the other two would return him to the cave after 3 and 5 hours of travel respectively. Assuming that the person is equally likely to opt for any of the openings at all times, what is...
  13. T

    Really difficult linear optimization problem from my book

    Here is the link to the problem http://i.imgur.com/3MDmG.jpg I really appreciate any help on this problem.
  14. S

    Worded Problem - Difficult to solve

    Terry has invented a new way to extend lists of numbers. To Terryfy a list such as [1, 8] he creates two lists [2, 9] and [3, 10], where each term is one more than the corresponding term in the previous list, and then joins the three lists together to give [1, 8, 2, 9, 3, 10]. If he starts with...
  15. D

    Difficult Limit

    Limit as x goes towards 0 for the function (e^x-1)^2/(sin(e^x-1)) Any help would be much appreciated
  16. O

    Simple but difficult geometry question (picture included) - First post here :)

    Hi all, first of all - my first post here. Nice to meet you all. I'm active on mymathforum if you guys post there from time to time. My name is Oria, I live in israel, I'm a math private teacher for pre uni students, and I study applied mathematics in holon institute of technology. Anyway...
  17. T

    Difficult Matrix Equation

    Hi I'm supposed to solve this matrix equation by GaussJordan elimination and I find it very difficult to see and carry out the row operations mainly because of the z's. If someone is able to help me I would truly appreciate it. zx1 + x2 + x3 = 1 x1 + zx2 + x3 = 1 x1 + x2 + zx3 = 1 z...
  18. D

    This should not be difficult, but I can't figure it out

    My girlfriend and I are trying to figure out how to divide costs in such a way that we both end up paying the same percentage of our income on each expense, but both of us are very math challenged and can't figure out how to do this(Thinking). To clarify, let's say I make 2500 per month, and she...
  19. F

    Difficult simplification problem

    I am trying to simplify this to express a as a function of t,r,p. It is killing me. Any help would be most appreciated. a^2=[(at)^2 + r^2]/p Edit: This problem is trivial, but I am also looking for a solution given the additional constraint, t=ab,
  20. X

    Difficult integral, please help.

    \int \frac{dx}{\sqrt{x^{4}+1}}