Expression Definition and 999 Threads

  1. fluidistic

    I don't understand an approximation in an expression in stat. mech.

    Homework Statement Hello guys, I fail to understand a mathematical approximation I see in a solved exercise. The guy reached a partition function of ##Z=\sum_{l=0}^\infty (2l+1) \exp \left [ -l(l+1) \frac{\omicron}{T} \right ]## and he wants to analyze the case ##T>> \omicron##. He states...
  2. topsquark

    MHB Finding Notation for Left Invariant Vector Fields on Lie Groups

    I'm sure this is a trivial notation question. I just can't seem to find the notation in my texts. Let L_a(g) = ag~\forall a, g \in G where a is fixed in G and G is a Lie group. (This defines the left action of G on itself.) A vector field X on a Lie group G is left invariant if (dL_g)(X(x))...
  3. E

    MHB How to Simplify a Fraction with Cubed Roots in the Numerator and Denominator?

    Help to obtain a simple form of the following expression: $$\frac{\sqrt[3]{a^2} -\sqrt[3]{ab}+\sqrt[3]{b}}{a+b}$$
  4. C

    Differential Eqn: Find an expression of the velocity of a rock.

    Homework Statement A 20 kg rock falls with the force of gravity acting on it. Another force acts on the rock (same direction as gravity) that is proportional to the velocity squared, 100v^2. Come up with an expression of the rock's velocity at any time t. Homework Equations Hint...
  5. T

    Using Newton's laws to find an expression for the angle of inclination

    Homework Statement Use Netwon's laws to find an expression for the angle of incilination theta at which the refrigerator starts to slide. Express your answer in terms of possible g, Us, Uk and m. Homework Equations Fnet=ma Ff=UFn The Attempt at a Solution I attached my attempt...
  6. I

    Finding an expression for a projectile's horizontal range

    Homework Statement A projecticle launced at an angle of θ to the horiz
  7. O

    MHB List all values of x for which each rational expression is undefined.

    List all values of x for which each rational expression is undefined: $$\frac{x^2-9}{x^2-3x-10}$$ Answer is 3, -3 q1) Are these -, and positive answer interchangeable ones because it is a rational expression so when I see rational that's going to signal it's going to need 2 answers (either...
  8. H

    MHB How Can I Simplify This Complex Mathematical Expression?

    Hello, I am having difficulty solving my math problems. Simplify the Expression and show how.. And kalkulate z²+w(2wz)²-(w+4z²-1)w³-(z+w²)(x-w²) And w=2 I know we have many ways doing it, an the more ways i can study, the bether i can understand this..
  9. Lolligirl

    MHB Designing NFA & DFA for (1001 + 110 + 11)* Language

    Hello everyone! I'm trying to design an NFA and then turn it into a DFA, and I'm not sure if I've done it correctly so far. Here is the question: "Present a transition diagram for an NFA for the language associated with the regular expression (1001 + 110 + 11)*. Your NFA must have no more than...
  10. F

    Derive an expression of Bohr radius in gravitational case

    Homework Statement Both Newton's gravitational law and Coulomb's law are inverse-square laws: The force of attraction between the sun (S) and Earth(E) has (G*m_S*m_E)/r^2, whereas the force of attraction between an electron and a proton in a hydrogen atom is (e^2)/(4*pi*epsilon_0*r^2). Derive...
  11. H

    MHB Simplifying a rational expression

    Hello, I am having difficulty solving my math problems. Simplify the expression: (12+r-r^2)/(r^3 +3r^2) The answer is (4-r)/r^2 I know that i can expand 12+r-r^2 as (-r+4)(r+3) But i cannot figure out the rest. Please help me. Thanks
  12. C

    Manipulating Equivalent Expressions -4/(4x+1)^(1/2) to (1/4+x)^(-1/2)

    Homework Statement Hi guys, I'm getting confused trying to manipulate an expression. Any help here would be hugely appreciated. How do I manipulate the expression -4 / (4x + 1)1/2 to become (1/4 + x)-1/2 The Attempt at a Solution I've tried dividing by -4 to get and used an index...
  13. F

    Lennard-Jones Potential: Derive an expression for equilibrium constant

    Edit: well this is frustrating, not sure why the itex things aren't working.. Edit2: I've attached a picture of the question at the bottom as well. Homework Statement The cohesive energy of a solid noble gas may be written as (See picture below) Derive an expression for the...
  14. S

    How to Fourier transform this expression?

    I have this expression: f(\tau) = 4 \pi \int \omega ^2 P_2[\cos (\omega \tau)] P(\omega) \, \mathrm{d}w \quad [1] where P_2 is a second order Legendre polynomial, and P(\omega) is some distribution function. Now I am told that, given a data set of f(\tau), I can solve for P(\omega) by either...
  15. mesa

    Looking for an expression for radicals

    I am trying to find a general expression for radicals, for example, √k=f(k) Does anyone know of any? Thanks!
  16. E

    Can I write this integral in "closed-form" expression?

    Hi all, I have this integral, and I wish to write it in a closed-form in order to be able to program it. The integral is: \int_{-\infty}^{\infty}e^{j2\pi f_c[a^{(u)}-a^{(m)}]}g(t[1+a^{(m)}]-kT_s-\tau_p^{(m,n)}) g(t[1+a^{(u)}]-lT_s-\tau_q^{(u,n)})\,dt where...
  17. B

    Simplifying expression with gamma matrix and slashes

    I am trying to simplify the expression \not p \gamma^\mu \not p. I believe the answer should be - \frac{1}{2} \gamma^\mu p^2, but I am not sure. Tom
  18. Trent21

    Solving a Quadratic Expression: How to Solve 2x^2+9x = -5

    2x^2+9x = -5 Solved, you can banish this thread now mods. 2x^2+9x = -5 With the given answers, nothing I can come up with matches it. I can't solve it like a normal quadratic, as it gives me no answer that matches those. And I can't factor it. Nothing that adds up to 9, that when you...
  19. M

    Why Is the Denominator in Fermat's Principle (c/n) Instead of (cn)?

    The expression gives time taken to reach a a distance ds in a medium. The expression has the dimension of time, But my question is how come the denominator is (c/n)? why it can't be (cn)? explain me.
  20. Maxo

    Factoring algebraic complex expression

    Homework Statement Factor the expression ac-bd+adi+bci Homework Equations The Attempt at a Solution We can factor the variable 'a' which gives: a(c+di)-bd+bci The common factor in the remaining terms is b, and if we also factor out b we get a(c+di)-b(d+ci) But this is not the...
  21. Y

    How to find the partial fractions for this expression?

    Homework Statement Find the partial fractions for this expression. (((n+1)*(sqrt(n)) - n*(sqrt(n+1))) / (n*(n+1))) The Attempt at a Solution The final answer is 1/sqrt(n) - 1/(sqrt(n+1)) My work: A/n - B/(n+1) = n*sqrt(n+1) - (n+1)*(sqrt(n)) I am subbing in n = -1 and n = 0 to solve for...
  22. TheSodesa

    Finding a limit of an expression when the denominator tends to zero.

    Homework Statement This problem is found in a chapter about rational functions in my review book. The expression is as follows: \lim_{x\rightarrow a} {\frac{2 x^2 + 5x - 3}{x - a}} = \ \text{L} where 'a' is a constant. I'm supposed to find a value of 'a' that allows the limit to...
  23. gfd43tg

    Minimum value of the expression

    Homework Statement Problem is posted as imageHomework Equations The Attempt at a Solution Hello, I am having some confusion over what is meant by 'type in the boxes the minimum value of the expression'. Does that mean take the derivative of the function? Or does that mean the value at which...
  24. kaliprasad

    MHB What integer makes $(x-a)(x-10) +1$ factorable as $(x+b)(x+ c)$?

    find integer a such that $(x-a)(x-10) +1$ can be factored as $(x+b)(x+ c)$ where b and c are integers
  25. C

    How Do You Simplify the Given Signal Expression?

    Homework Statement Evaluate (simplify) the following expression: y(t) = ∫0∞ e2(t + 2τ)δ(t + τ)dτ =Homework Equations Shortcut signal expression techniques, integration of an exponential signal and impulse signal, other techniques that are probably unknown to me The Attempt at a Solution...
  26. gfd43tg

    What is the Purpose of Using Arrays in Complex Expressions?

    Homework Statement I am working on problem 4 in the PDF attachment now, but I will show my code for 2 and 3 since they are related to 4. The values for 2 and 3 were given in the editor. Homework Equations The Attempt at a Solution 2. P = [1.6, 4, 2.9, -8]; N = 3; PextDown = repmat(P,3,1)...
  27. anemone

    MHB Simplify a trigonometric expression

    Simplify $\tan x\left(1-\sec \dfrac{x}{2} \right) (1-\sec x)(1-\sec 2x)\cdots(1-\sec 2^{n-1} x)$ at $n=8$.
  28. M

    General Expression for Round Metric on an N-sphere

    Homework Statement I want to know the expression for the round metric of an n-sphere of radius r Homework Equations I have obtained this for a 3-sphere dS^{2}=dr^{2}+r^{2}(d\theta_{1}^{2}+sin^{2}\theta_{1}d\theta_{2}^{2} +sin^{2}\theta_{1}sin^{2}\theta_{2}d\theta_{3}^{2}) The...
  29. C

    What is the expression for terminal speed in this homework statement?

    Homework Statement Homework Equations That is the solution: The Attempt at a Solution I think ε≠Bvl because ε = - dø/dt=- Bd(v.t)/dt, v is not constant. Why ε=Bvl?
  30. B

    Writing Boolean Expressions with Manual Override: Z = ABC & M

    Just a question if you had to write a boolean expression for a problem like this, A motor requires three conditons ABC to be high to start, but a manual override can start and stop it (M) what is the expression for Z so Z = ABC... how would you incorporate the overside switch.
  31. S

    MHB Finding an Expression for Y in a Linear Multistep Method

    consider the following LMM $$y_n-\frac{3}{2}y_{n-1}+\frac{1}{2}y_{n-2}=h(\frac{1}{2}f_n+\frac{1}{4}f_{n-1}-\frac{1}{4}f_{n-2})$$ which is applied to the initial value problem $$y'(t)=y(t),0\leq{t}\leq{1}\\ and\\ y(0)=1$$ How do i find an expression for $$y_n$$, if the starting values are...
  32. ChrisVer

    Solving Entropy Expression Homework Statement

    Homework Statement From the 2nd TD law: TdS= d(\rho V) + P dV - \mu d(nV) find that: S= \frac{V}{T} (\rho+P- \mu n) Homework Equations \frac{dP}{dT}= \frac{P+\rho - \mu n}{T} The Attempt at a Solution TdS= d(\rho V) + P dV - \mu d(nV) TdS= d[(\rho+ P- \mu n) V] -...
  33. H

    Integration of below expression

    Homework Statement it is capacitor charging expression..how to find its integration Homework Equations VL(t) = ∫_(T/2)^T▒〖Vme^(-T/2RC) 〗 dt The Attempt at a Solution result is 0.5...but how
  34. Govind_Balaji

    Prove a complex expression = 1, if log of the complex terms are equal

    Homework Statement If \frac{\log x}{b-c}=\frac{\log y}{c-a}=\frac{\log z}{a-b}, prove that x^{b+c-a}.y^{c+a-b}.z^{a+b-c}=1Homework Equations The Attempt at a Solution I solved a question similar to it in a way. So I tried this in the same way. The only difference between the two questions is...
  35. F

    Expression for the moment of inertia

    Homework Statement The thin, homogeneous bent rod has the mass m and the total length of 4b. It rotates with the angular speed of ω = ω0(24i + 12j - 6.0k) (only rotation) Determine the expression for the moment of inertia with consideration of the center of mass of the rod The figure...
  36. A

    Determine the value of expression (Calc-II)

    Please look picture. I represented the expression with this integral : integral of (1-x)^3 from 0 to 1. I got 0, which makes no sense... How should I proceed?
  37. A

    How can the electron density expression be simplified using momenta?

    Suppose we have a system with M nuclei and N electrons the electron density is defined as: \rho(\mathbf{r}) = \sum\limits_{\sigma = \uparrow, \downarrow} \sum\limits_{i}^N \psi^{*}_{i}(\mathbf{r\sigma})\psi_{i}(\mathbf{r\sigma}) i would like to know if it is valid...
  38. U

    Find minimum value of the expression

    Homework Statement Let n be a positive integer. Determine the smallest possible value of $$|p(1)|^2+|p(2)|^2 + ...+ |p(n+3)|^2 $$ over all a monic polynomials p with degree n. The Attempt at a Solution Let the polynomial be x^n+c_{n-1} x^{n-1} +...+ c_1x+c_0 p(1) =...
  39. Y

    Rate law expression with solids and liquids

    Hello Forum! I was wondering: In the rate law expressions, I could never find an example with a solid or a liquid in the reactants in my textbook (Chemistry by Zumdahl). I searched Chemistry (Raymond Chang) and Principles of Molecular Chemistry, without any success. What happens to...
  40. Y

    MHB Drawing and finding the value of postfix expression

    I am ending with no operator in the end. So 1000 160 would be the answer or what. I do not know what to do from here. Please help!
  41. I

    MHB How Can You Find an Expression for t(n)?

    hi all, Would it be possible for you to explain how to reach a solution for this question, or explain the process that you need to find the solution thank you
  42. T

    Engineering (DC motor derive ω expression with respect time

    Homework Statement I try to derive the expression of ω with respect to t, but the problem is the armature current Ia or the flux is unknown. I don't know how to solve it. Anyone could give me ideas? Thanks a lotHomework Equations τ=J(ω/t) Vs=IaRa+Ea T=KEøIa Ea=KEøω
  43. Y

    MHB How to read this expression "A graph G = (V ,E)"

    How to read this expression "A graph G = (V ,E)"
  44. D

    How is Kp(T) Derived for Dissociation of H2O at High Temperatures?

    Hello I'm solving previous exams and there is this exercise that appears in almost every exam : Homework Statement Suppose v moles of a gas H2O are enclosed in a constant volume V at a low temperature so the gas is in aN undissociated state. At highest temperatureS, H2O molecules are...
  45. anemone

    MHB Factorization of an expression

    Factorize the expression $(1+a+\cdots+a^n)^2-a^n$.
  46. M

    An expression about kinetic energy

    Hi, all. Here is an expression about kinetic energy from analytical dynamics of Haim Baruh which confuses me. "Consider a particle and the case which the kinetic energy is only quadratic in terms of velocity of the particle. We take the differential form of work-energy principle and remove...
  47. B

    MHB Is this Tree of Algebraic Expression Correct?

    Hello I just wanted to see if I did this right. I've come up with two trees and I'm pretty sure one of them is correct, I'm just not sure. Construct the Tree of the algebraic expression: ((x - 2) + 3) / ((2 - (3 + y)) x (w - 8))
  48. A

    MHB State the differences between an expression and its simplified equivalent.

    State the differences between an expression and its simplified equivalent.
  49. S

    Proof of the nontrivial expression

    I'm looking for a proof of a validity of the inequation: (n-1)\sum_{i=1}^{n}x_{i}^{2}\neq 2\sum_{i=1,j=1,j<i}^{n}x_{i}x_{j} Assumptions: n\geq 2 \exists (i,j),x_{i}\neq x_{j} i=1,...,n j=1,...,n I have no idea how to prove those non-trivial expressions.
  50. gfd43tg

    AC Op-Amp output voltage expression in time domain

    Homework Statement For vi(t) =V0 cosωt, obtain an expression for vout(t) in the circuit below and then evaluate it for V0 = 4 V, ω = 400 rad/s, R = 5 kΩ, and C = 2.5 μF. Homework Equations The Attempt at a Solution For this problem, I am having difficulty taking that second term...
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