Inequality Definition and 1000 Threads

  1. B

    Can the Inequality x^x + y^y < (x+y)^(x+y) be Proven Algebraically?

    Is it possible to prove this: x^x + y^y < (x+y)^(x+y) for every x,y >=1 ?
  2. C

    Complex number inequality graph

    Homework Statement How would Re(z)<0 be graphed? Homework Equations Re(z) is the real part of z The Attempt at a Solution It looks similar to y>x, but only shaded in the third quadrant, how can this be explained? not relevant anymore
  3. F

    (Algebra) Quantum Theory - Cauchy-Schwartz inequality proof

    Homework Statement Given two arbitrary vectors |\phi_{1}\rangle and |\phi_{2}\rangle belonging to the inner product space \mathcal{H}, the Cauchy-Schwartz inequality states that: |\langle\phi_{1}|\phi_{2}\rangle|^{2} \leq \langle\phi_{1}|\phi_{1}\rangle \langle\phi_{2}|\phi_{2}\rangle...
  4. anemone

    MHB Prove Inequality for $0<x<\dfrac{\pi}{2}$: Math Challenge

    For $0<x<\dfrac{\pi}{2}$, prove that $\dfrac{\pi^2-x^2}{\pi^2+x^2}>\left(\dfrac{\sin x}{x}\right)^2$. I personally find this challenge very intriguing and I solved it, and feel good about it, hehehe...
  5. A

    Teacher told to set absolute value inequality to equal 0

    So I was helping my sister on homework and there was this problem: 2 abs(2x + 4) +1 > or equal to -3 teacher told her to ignore the -3 and just set it equal to zero. Soo should you? This question got me confused. can't you just go about solving, bringing the 1 to the left and then dividing by 2...
  6. E

    Prove that for a,b,c > 0, geometric mean <= arithmetic mean

    Homework Statement Let ## a,b,c \in \mathbb{R}^{+} ##. Prove that $$ \sqrt[3]{abc} \leq \frac{a+b+c}{3}. $$ Note: ## a,b,c ## can be expressed as ## a = r^3, b = s^3, c = t^3 ## for ## r,s,t > 0##. Homework Equations ## P(a,b,c): a,b,c \in \mathbb{R}^{+} ## ## Q(a,b,c): \sqrt[3]{abc} \leq...
  7. K

    Inequality X^n<Y^n if x<y and n is odd

    Hi All, Question : Prove that xn<yn , given that x<y and n is odd . Attempt at solution : Assumptions: y-x>0 y2>0 x2>0 So y2x<y3 & x3<x2y So i need to prove that x2y<y2x i.e need to prove then y2x-x2y>0 then yx(y-x)>0, from assumptions y-x>0 so i need to prove that yx>0, so i have 3 cases...
  8. K

    Solve Inequality x+3^x<4 | Logical & Analytic Ways

    Hi all, I was trying to solve the Inequality x+3x<4 and i found the solution to be x<1, using trial and error. Is there another Logical way or analytic one. Thanks
  9. Albert1

    MHB Can the Inequality $x,y,z>1$ be Proven with a Hint of 48?

    $x,y,z>1$ please prove : $\dfrac{x^4}{(y-1)^2}+\dfrac{y^4}{(z-1)^2}+\dfrac{z^4}{(x-1)^2}\geq 48$
  10. gfd43tg

    Schwarz inequality with bra-ket notation

    Homework Statement Homework EquationsThe Attempt at a Solution Hello, I just want to make sure I am doing this right $$<a|b> = a_{x}^{*}b_{x} + a_{y}^{*}b_{y} + a_{z}^{*}b_{z}$$ $$= [(1-i)|x>][-i|x>] + (2 |y>)(-3 |y>) + (0|z>)(|z>)$$ $$=(-i + i^{2})|x> - 6 |y> + 0|z>$$ $$=(-1-i)|x> - 6 |y>...
  11. A

    Solving Inequality: -∞ < a < -3 ∨ -1 < a < ∞

    Hi I'm trying to solve this inequality |1/(2+a)| < 1. 1/(2+a) < 1 ∨ 1/(2+a) > -1 1 < 2+a a > -1 and 1 > -2-a 3 > -a a > -3 I know that the boundaries are -∞ < a < -3 ∨ -1 < a < ∞ What have I done wrong? thanks in advance
  12. R

    Entanglement and Bell’s inequality Question

    Forgive the layman type question but I was doing some reading on Bell's inequality and how it disproves the hidden variable hypothesis in entanglement. The example I looked at was from YouTube I understand the principle of how bell's theorem works and how the tests done on polarisation of...
  13. Cosmophile

    Serge Lang: Inequality Problem

    Hello, all. I am reading Serge Lang's "A First Course in Calculus" in order to get a better understanding of the topic. I thought I would read his review of fundamental concepts, and, naturally, it has been a breeze so far. However, I am stumped when trying to work out this problem: I do not...
  14. anemone

    MHB Is the Absolute Value Inequality $|4x-5|-|3x+1|+|5-x|+|1+x|=0.99 Solvable?

    Show that the equation $|4x-5|-|3x+1|+|5-x|+|1+x|=0.99$ has no solutions.
  15. H

    MATLAB Unexpected inequality in Matlab

    In the program below, the result of "difr" is not zero but according to the definition of qx in the second line, I expect it to be zero (because qx^2+ky^2=(\frac{ef-u}{hbarv_f})^2). What is the problem? ef=1;hbarv_f=658;ky=0.0011;u=2.5; qx=sqrt(((ef-u)/hbarv_f)^2-ky.^2)...
  16. V

    Proving Inequality $$4x^4 + 4y^3 + 5x^2 + y + 1 \ge 12xy$$

    Homework Statement [/B] this is the problem , if x and y are real positive numbers , I need to prove $$4x^4 + 4y^3 + 5x^2 + y + 1 \ge 12xy$$ Homework Equations [/B] $$x^2 + y^2 \ge 2xy$$ (Variation of AM GM Theorem) The Attempt at a Solution but $$x^2 + y^2 \ge 2xy $$, so $$6x^2 + 6y^2 \ge...
  17. anemone

    MHB Can $k>1$ Prove This Inequality?

    Prove that for all integers $k>1$: $\left(\dfrac{1+(k+1)^{k+1}}{k+2}\right)^{k-1}>\left(\dfrac{1+k^k}{k+1}\right)^{k}$
  18. LiHJ

    Quadratic Inequality: Solve for 4/m-2/n Without a Calculator

    Homework Statement Dear Mentors and PF helpers, Here's the question: The roots of a quadratic equation $$3x^2-\sqrt{24}x-2=0$$ are m and n where m > n . Without using a calculator, a) show that $$1/m+1/n=-\sqrt{6}$$ b) find the value of 4/m - 2/n in the form $$\sqrt{a}-\sqrt{b}$$ Homework...
  19. powerof

    Inequality involving series using Cauchy-Schwartz

    Homework Statement [/B] Prove the following: \sum_{k=1}^{\infty}a_{k}^{2} \leq \left ( \sum_{k=1}^{\infty}a_{k}^{2/3} \right )^{1/2} \left ( \sum_{k=1}^{\infty}a_{k}^{4/3} \right )^{1/2} Homework Equations [/B] The following generalization of Cauchy-Schwarz present in the text (containing...
  20. Math Amateur

    MHB Trigonometric Inequality in Tom Apostol's Book

    In Tom Apostol's book "Calculus: Volume 1 (Second Edition) he uses the following inequalities: 0 \lt \cos x \lt \frac{ \sin x }{x} \lt \frac{1}{ \cos x } ... ... ... (1) in order to demonstrate that: \lim_{x \to 0} \frac{ \sin x }{x} = 1... ... BUT ... ... how do we prove (1) ... That is how...
  21. K

    MHB Graphing Inequality : lx-yl + lxl - lyl ≤ 2

    Sketch the region in the plane consisting of all points (x,y) such that lx-yl + lxl - lyl ≤ 2 I don't know exactly the most appreciated solution to this kind of problem. Can you guys show me a clear answer and if possible, a careful graph please?
  22. Demystifier

    Bell's inequality for non-physicists

    I am reading the popular-science book A. Zeilinger, Dance of the Photons In the Appendix I have found a surprisingly simple derivation of Bell's inequalities, which, I believe, many people here would like to see. Here it is
  23. anemone

    MHB Proving Inequality with Positive Real Numbers $x,\,y,\,z$

    Let $x,\,y,\,z$ be positive real numbers such that $xy+yz+zx=3$. Prove the inequality $(x^3-x+5)(y^5-y^3+5)(z^7-z^5+5)\ge 125$.
  24. LiHJ

    Quadratic inequality involving Modulus Function

    Homework Statement Dear Mentors and PF helpers, I saw this question on a book but couldn't understand one part of it. Here the question: Solve the following inequality I copied the solution as belowHomework Equations The Attempt at a Solution I don't understand why the numerator in step...
  25. anemone

    MHB Inequality: $\dfrac{\ln x}{x^3-1}<\dfrac{x+1}{3(x^3+x)}$ for $x>0,\,x\ne 1$

    Prove that $\dfrac{\ln x}{x^3-1}<\dfrac{x+1}{3(x^3+x)}$ for $x>0,\,x\ne 1$.
  26. edpell

    Progress on Explaining Bell's Inequality

    Is here any progress on explaining Bell's Inequality? I do not mean explaining what it is, I mean how it works.
  27. L

    Prove Minkowski's inequality using Cauchy-Schwarz's

    Homework Statement For u and v in R^n prove Minkowski's inequality that \|u + v\| \leq \|u\| + \|v\| using the Cauchy-Schwarz inequality theorem: |u \cdot v| \leq \|u\| \|v\|. Homework Equations Dot product: u \cdot v = u_1 v_1 + u_2 v_2 + \cdots + u_n v_n Norm: \|u \| = \sqrt {u \cdot u}...
  28. anemone

    MHB Is There an Inequality Challenge with Real Numbers?

    Let $a,\,b,\,c,\,d$ be real numbers such that $abcd=1$ and $a+b+c+d>\dfrac{a}{b}+\dfrac{b}{c}+\dfrac{c}{d}+\dfrac{d}{a}$. Prove that $a+b+c+d<\dfrac{b}{a}+\dfrac{c}{b}+\dfrac{d}{c}+\dfrac{a}{d}$.
  29. N

    What is the significance of Bell's Inequality Theorem in quantum mechanics?

    I read the following article (I think the author writes on this forum) and thought I understood the reasoning (at least a 0.333 chance of a match, whatever the setting, quantum mechanics for a 120 degree difference in angle predicts a 0.25 chance of a match, measurement shows it to be around...
  30. B

    Can You Solve This Logarithmic Inequality?

    Homework Statement Here is the problem : https://www.dropbox.com/s/otzzne7wjyuqa5o/question.jpg?dl=0 I've tried solving this inequality but alas,nothing...It's an exam question for my student,and for my great shame,I have no idea how to solve it :(
  31. B

    Inequality Proof: Is Multiplying Both Sides Valid?

    Hello, In Principles of Mathematical Analysis, the author is attempting to demonstrate that, if ##x > 0## and ##y < z##, then ##xy < xz##, which essentially states that multiplying by a positive number does not disturb the inequality. I am hoping someone will quickly denounce this with an...
  32. AdityaDev

    Sandwich Theorem: changing inequality

    Homework Statement Using sandwich theorem evaluvate: $$\lim_{x\rightarrow \infty} \frac{x+7sinx}{-2x+13}$$ Homework Equations Sandwich theorem The Attempt at a Solution ##-7 \leqslant 7sinx \leqslant 7## ##x-7 \leqslant x+7sinx \leqslant x+7## Now my doubt: I want to divide the expression by...
  33. K

    MHB Can this inequality be proven under given conditions?

    Hallo, could comeone help me to proof this inequality: \frac{m!}{\lambda^{m+1}} \cdot \sum_{j=0}^{m} \frac{\lambda^j}{j!} \leq \frac{2}{\sqrt{\lambda}} . under condition m+1 < \lambda . \lambda is real and m is integer.
  34. K

    MHB How to Prove This Complex Inequality Involving Factorials and Sums?

    Hallo, can someone help me to proof this inequality: (\lambda-(m+1)) \cdot \frac{m!}{\lambda^{m+1}} \cdot \sum_{j=0}^m \frac{\lambda^j}{j!} (m+1-j) \leq \frac{\lambda}{\lambda-m} with condition m+1 < \lambda . \lambda is real und m is integer.
  35. K

    MHB Can This Complex Inequality Be Proven?

    Hallo, can someone help me to proof this inequality: 1-(\lambda-(m+1)) \cdot \frac{m!}{\lambda^{m+1}} \cdot \sum_{j=0}^{m} \frac{\lambda^j}{j!} \leq \frac{\lambda}{(\lambda-(m+1))^2} under condition m+1 < \lambda .
  36. M

    MHB Generalized Holder Inequality: Proving the Inequality for Arbitrary Exponents

    Let $a_i \in \mathbb R^n$ with $a_i = (a_{i}^j)_{j = 1 ... n} = (a_{i}^1, ... ,a_{i}^n)$ for $i = 1, ... , k$ and let $p_1,...,p_k \in \mathbb R_{>1}$ with $\frac1{p_1}+ ... + \frac1{p_k} = 1$ Then show the following inequality by assuming that there are for every $i = 1, ... ,k$ one $N \in...
  37. P

    Exploring Bell's Inequality: An Experiment with Entangled Photons

    Hi. After spending an entire day watching videos and reading websites, I'm unable to find the details of a bell's inequality experiment with regards to photons. Could someone please describe such an experiment. What I've learned is that a photon is emitted, say blue. The blue photon is used to...
  38. jerromyjon

    Understanding the Bell Inequality and its Impact on Quantum Mechanics

    I went through a paper last week about the Bell inequality and how it is incompatible with QM. Something along the lines of probability in classical regards being 1/3 but in quantum mechanics it is 1/4. It went into some basic principles of how this is determined through quantum entanglement to...
  39. datafiend

    MHB Solution Set in interval notation for inequality

    HI all, I have the equation, 6x^2-2>9x for which I'm to find the solution set in interval notation. I've rewritten the inequalty as 6X^2-9x-2=0. I tried to factor, but no go. Then I used the quadratic and got 9+/- rad(129)/-18. The answers I get for x are -1.1309 and .1309. The calculator...
  40. G

    QM prediction violating Bell’s inequality

    I have read many explanations of Bell’s proof that mention in passing something like “According to QM, the correlation between measurements of spin at different angles should be given by the cosine of the angle between them.” Sometimes they talk about 1-cos(x)/2. Sometimes they talk about...
  41. M

    MHB Prove Inequality: Nonnegative Reals {x}_{1}...{x}_{n} Sum to 1

    There are nonnegative real numbers {x}_{1}, {x}_{2}, ... , {x}_{n} such that {x}_{1} + {x}_{2} +...+ {x}_{n} =1 where n \ge 2. Prove that \max\left\{{x}_{1},{x}_{2},...,{x}_{n}\right\} \cdot (1+2 \cdot \sum_{1\le i<j\le n}^{}\min\left\{{x}_{i}, {x}_{j}\right\}) \ge 1 . I noticed that for...
  42. Fallen Angel

    MHB How can we prove the derivative inequality for f(x)=sin(x)/x?

    Hi, My first challenge was not very popular so I bring you another one. Let us define f(x)=\dfrac{sin(x)}{x} for x>0. Prove that for every n\in \mathbb{N}, |f^{(n)}(x)|<\dfrac{1}{n+1} where f^{n}(x) denotes the n-th derivative of f
  43. DavideGenoa

    Is There an Error in Kolmogorov and Fomin's Trigonometric Inequality Proof?

    I read that, for ##\delta>0##, if ##\delta<z\leq\pi##, then ##\sin\frac{z}{2}\geq\frac{2\delta}{\pi}##. I cannot prove it. I know that ##\forall x\in\mathbb{R}\quad|\sin x|\leq |x|##, but that does not seem useful here... Thank you so much for any help!
  44. Dethrone

    MHB Sketch Inequality: Region of $(x,y)$ Points

    From the differentiation section of my calculus textbook: Sketch the region in the plane consisting of all points $(x,y)$ such that $$2xy\le\left| x-y \right|\le x^2+y^2$$ I have tried to look at the cases: Case 1: $x>y$ $$2xy\le x-y\le x^2+y^2$$ $$0\le (x-y)-2xy\le x^2+y^2-2xy$$ Now I have...
  45. evinda

    MHB Why does the inequality stand if there are no common elements?

    Hi! (Smirk) $$x \in \mathcal{P}A \cup \mathcal{P} B \rightarrow x \in \mathcal{P}A \lor x \in \mathcal{P}B \rightarrow x \subset A \lor x \subset B \rightarrow x \subset A \cup B \rightarrow x \in \mathcal{P} (A \cup B)$$ So, $\mathcal{P}A \cup \mathcal{P}B \subset P(A \cup B) $. The equality...
  46. Vanadium 50

    Is Increasing Inequality Acceptable If Everyone Benefits?

    MIT's Technology Review ran an article on inequality, where they argue that a) it is bad, and b) it is technologically driven, in that it raises some people's income and wealth more than others. I see a tension in these. Suppose I could wave a magic wand, and double the income of everyone...
  47. O

    Is the Solution to the Absolute Value Inequality x^2<4 then |x|<=2 Correct?

    Question: True or False If x^2<4 then |x|<=2 My solution: I get -2<x<2 when I solve the problem so it should be false. Yet the text says its true? Is this a mistake? If |x| is equal to 2 then it should be a closed interval, not an open interval which seems to be correct to me.
  48. kaliprasad

    MHB Inequality: Prove $a^4+b^4+c^4 \ge abc(a+b+c)$

    for positive a , b, c prove that $a^4+b^4+c^4 \ge abc(a+b+c)$
  49. B

    Verifying an Inequality Involving the Complex Exponential Function

    Demonstrate that ##|e^{z^2}| \le e^{|z|^2}## We have at our disposal the theorem which states ##Re(z) \le |z|##. Here is my work: ##e^{|z|^2} \ge e^{(Re(z))^2} \iff## By the theorem stated above. ##e^{|z|^2} \ge e^x## We note that ##y^2 \ge 0##, and that multiplying by ##-1## will give us...
  50. E

    Solve AM GM HM Inequality for a+b+c=0

    Homework Statement If a+b+c=0 then ( (b-c)/a + (c-a)/b + (a-b)/c )( a/(b-c) + b/(c-a) + c/(a-b) ) is equal to: Ans: 9 Homework Equations AM>=GM>=HM Equality holds when all numbers are equal. The Attempt at a Solution I tried using AM>=GM. ( (b-c)/a + (c-a)/b + (a-b)/c + a/(b-c) + b/(c-a) +...
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