Variable Definition and 1000 Threads

This is something that when I see the work done it makes sense, but I find it difficult to do myself. I'm also aware there is an explicit formula for doing this but that involves Jacobians and a well-defined inverse, so I think it's more intuitive to do it step-by-step. Problem: Suppose $X...

Professor Roberto has to take an oral examination. The grading scale is as follows: 5: = best and 1: = worst. At most he only gives the note 4. Each student under review is questioned if he is a Lakers fan. The student's grade is based on his answer (is a fan / not a fan) and on the language in...

Homework Statement X is uniformly distributed over [-1,1]. Compute the density function f(y) of Y = 2X2 + 1. Homework Equations The Attempt at a Solution FY(Y) = P(Y < y) = P(2X2 + 1 < y) = P(X < +\sqrt{1/2(y-1)} = FX(+\sqrt{1/2(y-1)}) We have that f(x) = 0.5 for -1 < x <...

Hi guys, first time poster. My question is; How would a constant damping provided by an electromagnet affect the damping ratio (and logarithmic decrement) amplitude? And how would increasing the current through the electromagnet affect the damping? So far I've found Biot-Savart's Law which...

Homework Statement Use * to show --> Homework Equations The Attempt at a Solution So I've begun by trying to take the 2nd derivative of \frac{\partial z}{\partial r}=\cos\theta\frac{\partial z}{\partial x}+\sin\theta\frac{\partial z}{\partial y} Which gives me this...

Homework Statement An electric circuit comprises two series resistors A and B, the first of which has a given resistance R_A and the second variable resistance R_B, over which a constant DC voltage U is added. How shall the resistance R_B be selected so that the power P developed in resistor B...

Just wondering if the Java experts here could help me. As part of a project I'm making a function [FONT="Courier New"]rand9() that returns a pseudo-random number 0 through 9. The problem is that each time it's called I need a certain number to increment so that it can generate a new (not...

Hi All, I built this shaker table: and I am now trying to change the amplitude so that it is no longer fixed but instead variable. The frequency I can change but the amplitude is fixed given this design. Does anyone have any suggestions on how to be able to change the amplitude so I can...

Homework Statement A balloon of mass M contains a bag of sand of initial mass ##m_o##. The balloon experiences a constant upthrust and is initially at rest and in equilibrium: the upthrust compensates exactly for the gravitational force. At time t=0, the sand is released at a constant rate...

Homework Statement There is a uniform but variable magnetic field ##\vec{B}=(B_0 t)(-\hat{k})##, in a cylindrical region, whose boundary is described by ##x^2+y^2=a^2##. ##\displaystyle \int_P^{Q} \vec{E} \cdot \vec{dy}## is (see attachment 1) A)0 B)##\frac{\pi}{4}(B_0 a^2)##...

This is my first time posting in this forum, I am not very familiar with the rules. I am a year 1 physics student, and I had only taken 1 variable calculus( I also know some basic linear algebra, e.g. how to calculate eigenvector in 2x2 situation, don't know Gram–Schmidt process for...

Homework Statement Give a method for generating a random variable with distribution function F(x) = 1/2(x+x^{2}) 0<x<1 The Attempt at a Solution From what i can tell i am supposed to do something like: Let U be a uniformly distributed random variable over (0,1). U =...

The cumulative distribution function of a continuous random variable is given as follows: 0 0 ( ) 0 5 5 1 5 X if x x F x if x x           a. Determine and name the density function of . [02] b. Use both and ( ) X F x to find P(X  3) . [05] c. Find the variance of ...

Homework Statement (Everything here is frequency dependant, but I have left off the v from all the variables to minimise chance of typos - hopefully that is ok but please let me know if not and I will try and retype!) The equation of radiative transfer is dI/dτ = -I + S We guess...

Is there an easy way of designing a band pass filter whose pass band could be varied over a certain band?? The pass band is in MHz range. Thanks

f(x)=1, θ-1/2 ≤ x ≤ θ+1/2 Given that Z=(b-a)(x-θ)+(1/2)(a+b) how would you show that Z has a continuous uniform distribution over the interval (a,b)? Any help would be much appreciated.

Calculate max and min value of the function $$f(x,y)=x^2+y^2-2x-4y+8$$ in the range defined by the $$x^2+y^2≤9$$ Progress: $$f_x(x,y)=2x-2$$ $$f_y(x.y)=2y-4$$ So I get $$x=1$$ and $$y=2$$ We got one end point that I don't know what to do with $$x^2+y^2≤9$$ If I got this right it should be a...

Homework Statement X is a normal random variable with mean 1, variance 4. 1. Find P( X(X-1) > 2 ) 2. Find a value 'a' for which P(|X| > a ) = .25 The Attempt at a Solution I had no idea how to start 1. For 2, i got this far then got stuck: P(|X| > a) = 1 - P((X-1)/2 <=...

Homework Statement Determine if sequence converges or diverges, if it converges find its limit. a (sub) n= (3^(n+2))/(5^(n)) The Attempt at a Solution The only things I've tried doing thus far is setting the sequence up as a function and letting x approach infinity. I then tried using l...

so i have swap.s .text main: la $a0,n1 la $a1,n2 jal swap li $v0,1 # print n1 and n2; should be 27 and 14 lw $a0,n1 syscall li $v0,11 li $a0,' ' syscall li $v0,1 lw $a0,n2 syscall li $v0,11 li $a0,'\n' syscall li $v0,10 # exit syscall swap: L1: .data n1: .word 14 n2...

Homework Statement lim(x,y)-(1,0) ln((1+y^2)/(x^2+xy)) Homework Equations The Attempt at a Solution if i just substitude x and y i get ln (1)= 0 so is the limit 0?

I have the following integral: \int_0^{f(x,y)}{f' \sin(y-f')df'} Now suppose that f(x,y) = x*y, my question is how do I write the integral in terms of x and y only? Can I do something like this? Since df=\frac{\partial f}{\partial x}dx+\frac{\partial f}{\partial y}dy we can obtain...

First of, I apologize for the vague title, I didn't know how to summarize this issue. Homework Statement Suppose that the interest rate obtained in month i is a random variable Ri with the uniform distribution on [0.01, 0.03], where R1,R2, . . . are independent. A capital of 1 unit...

Homework Statement ((1/3)(y^3))+(1/y)=.5*ln((x^2)+1) Solve in terms of y Homework Equations The Attempt at a Solution I am in college differential equations, and i just can't solve in terms of y. y teacher wants that...i tried wolfram alpha, etc. How on Earth do you factor this...

Hi, I'm trying to solve this equation inside of Maple: http://screencast.com/t/EeqzLhxS for gamma(s) I assign variables to each of the values like this:http://screencast.com/t/DBLS8BH6R When I try to solve I get this weird answer with a new _z variable...

I have the following recurrence equation, where C is just some constant: $$ T(n) = 0, n = 1\\ T(n) = T(\frac{n-1}{2}) + 2C, n > 1 $$ Using a top-down approach to unrolling the equation to find the pattern, I get: $$ T(n) = T(\frac{n-k}{2^{k}}) + 2kC $$ Now I want to solve for k and associate...

Hi, I am working on an economics paper, and I find that the following first order condition for my variable of interest (\mu \in [0,1]): \frac{\lambda(1+\mu)}{(1-\mu)}=N-x\frac{(1+\mu)}{\sqrt{\mu}} I would ideally like to provide an explicit solution, but unfortunately, this would amount to...

I have a problem that I normally find solutions to via trial and error, and they usually aren't optimized, but was wondering if there is a better way to solve this and optimize. My application is specific but this is the best way I can describe the problem. Forgive me if it doesn't make...

Homework Statement I'm trying to find the value of a variable which happens to be an exponent. Homework Equations 230,000=1500\frac{(1+.00077)^n-1}{.00077} I believe I need to use logarithms to get to my answer, but I've reviewed logarithm rules and I'm stuck. The Attempt at a...

Dear all, I am stuck with an apparently easy system of 3 simultaneous equations that has to be solved in x,y and z. The system is the following: ##(y+z) / ((x+y+z)²)=ax^{α-1}## ##(x+z) / ((x+y+z)²)=by^{α-1}## ##(x+y) / ((x+y+z)²)=cz^{α-1}## The parameters (a,b,c) and the variables (x,y,z) are...

many transition elements have variable oxidation state like Fe.what is the exact cause for this?they may not obey the octet rule,but what is the reason behind this?Also,elements like nitrogen are not transition elements and still show variable valency.what will be the electronic configuration of...

Homework Statement A trial consists of throwing two dice. The result is counted as successful if the sum of the outcomes is 12. What is the probability that the number of successes in 36 such trials is greater than one? What is this probability if we approximate its value using the Poisson...

Homework Statement So I had to find out N=Noe-ux Where No=1.5,e is the elementary charge, u=-0.068 and x=0.07 I came to the answer 1.221 Now I need to find x if u =-0.036, N=1.221 and No remains 1.5Homework Equations The Attempt at a Solution I reduce the equation to the following...

Homework Statement Why does the extra phase factor cancel out? Is it because you are multiplying the wave-function with the extra phase factor by its conjugate and if so, why should it matter that the extra phase factor is independent of x? All relevant information, the solution and equation...

I have to do these 2 problems for homework, but I can't figure them out. Any help would be appreciated. 1. The motorcycle is traveling at 1m/s when it is at A(the origin). If the speed is then increased at \dot{V} = .1 m/s^2, determine its speed and acceleration at the instant t = 5 seconds...

Hey everyone :) Got stuckon a calc question and needed some help, my test is coming up :S Please & thankyouu! Here's the question: Evauate the limit by change of variable: lim (x-->4) [(x^1/2)-2] / [(x^1/3)-8] The answer in the back of the book is 1/12. It MAY be wrong though...

I have the following summation where a is a positive constant and can be > 1 $$ \sum_{k=2}^{n}a^{n-k} $$ I am trying to find a general formula for this summation, which turns out to be a geometric series with a as the common ratio. I have worked out the following: $$ \sum_{k=2}^{n}a^{n-k} =...

a=4,b=3 and c=-2 5ab/12-2cb:confused:

Evaluate the variable expression when a=3,b=1 and c=-2 b^2-4ac. This is new to me so please explain how to do this.

Homework Statement A variable air-filled capacitor of the type used in tuning radios is shown. Alternate plates are connected together, one group fixed in position (shown in dark grey), the other group capable of rotation (shown in light gray). Consider a pile of n plates of...

Good day to all Physics Forums members, I am currently undertaking a project which involves the use of a Linear Variable Differential Transformer (LVDT) to measure the distance an object makes between two points. My setup is as follows: LVDT Type: Solartron DC50 with sensitivity of 6.158...

Author: A.I. Markushevich Title: Theory of Functions of a Complex Variable Amazon link: https://www.amazon.com/dp/082183780X/?tag=pfamazon01-20 Prerequisities: Real Analysis Level: Undergrad Table of Contents of Volume I: Basic Concepts Introduction Analytic Functions of a Real...

Hii please help me to Solve problems diffrentiability of function with two variable with one method.

Problem: The problem asks to find which frequencies a listener, whom is receiving sound waves in the same direction from two variable-frequency speakers 50ft and 55ft away, will not hear anything at all. Solution (so far): My approach is to find an expression for the wave coming from each...

Hi Would it be possible to make an inverter, with the output dependant on a digital resistor? Simon

In the page that I attached, it says "...while at the continuity points x of F_x (i.e., x \not= 0), lim F_{X_n}(x) = F_X(x)." But we know that the graph of F_X(x) is a straight line y=0, with only x=0 at y=1, right? But then all the points to the right of zero should not be equal to the limit of...

I have 3 problems I'm stuck on. Anyone please help. B=1/9(one ninth)pi to the 2nd power t and trying to solve for t Then this one, c=1/2(half)mr solving for m And solve the formula for the indicated variable P=a+2b+4c, for a.

1. In scanning electron microscopy photography, a specimen is placed in a vacuum chamber and scanned by an electron beam. Secondary electrons emitted from the specimen are collected by a detector and an image is displayed on a cathode-ray tube. This image is photographed. In the past a 4- ...

Homework Statement I have this 4x4 determinant and usually these are just mechanical work, until I stumbled upon one containing x, how should one go about solving these type of determinants? [x 2x 4 x ] [1 2 2x 1 ] [2x x-1 2 3x] [ 2 x+1 x+3 x-1] What are the different values of...

Hello everyone! I'm looking at the following random variables: $Z_1$ is normally distributed with zero mean and variance $\sigma _1 ^2$ $Z_2$ is normally distributed with zero mean and variance $\sigma _2 ^2$ $B$ is Bernoulli with probability of success $p$. $X$ is a random variable that...