What is Inequalities: Definition and 328 Discussions

In mathematics, an inequality is a relation which makes a non-equal comparison between two numbers or other mathematical expressions. It is used most often to compare two numbers on the number line by their size. There are several different notations used to represent different kinds of inequalities:

The notation a < b means that a is less than b.
The notation a > b means that a is greater than b.In either case, a is not equal to b. These relations are known as strict inequalities, meaning that a is strictly less than or strictly greater than b. Equivalence is excluded.
In contrast to strict inequalities, there are two types of inequality relations that are not strict:

The notation a ≤ b or a ⩽ b means that a is less than or equal to b (or, equivalently, at most b, or not greater than b).
The notation a ≥ b or a ⩾ b means that a is greater than or equal to b (or, equivalently, at least b, or not less than b).The relation "not greater than" can also be represented by a ≯ b, the symbol for "greater than" bisected by a slash, "not". The same is true for "not less than" and a ≮ b.
The notation a ≠ b means that a is not equal to b, and is sometimes considered a form of strict inequality. It does not say that one is greater than the other; it does not even require a and b to be member of an ordered set.
In engineering sciences, less formal use of the notation is to state that one quantity is "much greater" than another, normally by several orders of magnitude. This implies that the lesser value can be neglected with little effect on the accuracy of an approximation (such as the case of ultrarelativistic limit in physics).

The notation a ≪ b means that a is much less than b. (In measure theory, however, this notation is used for absolute continuity, an unrelated concept.)
The notation a ≫ b means that a is much greater than b.In all of the cases above, any two symbols mirroring each other are symmetrical; a < b and b > a are equivalent, etc.

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  1. facenian

    I Problem with CHSH's version of Bell's inequalities

    Though I don't have access to the original 1969 paper, I think the way the inequality is ussually derived is not correct since the argument goes as follows: $$-2≤ A(a,\lambda)[B(b,\lambda)-B(b',\lambda)]+A(a',\lambda)[B(b,\lambda)+B(b',\lambda)]≤2$$ the first mistake in this inequality is the...
  2. Einstein's Cat

    B Inequalities of complex number

    I am under the impression that the following cannot be stated, a < b, if the a term is a complex number and the b term is either a natural number or a complex number, or any other type of number for that matter. Firstly am I correct? Secondly, if I am, does there exist a theorem of some sort...
  3. T

    Where do mathematical inequalities come from?

    what do you think are the inspirations or motivations that lead to inequality statements like am-gm, bernoullie's inequality, etc...? are they inspired by physics, engineering...? learning them for the first time made me wonder where they came from. thanks!
  4. V

    Solving Polynomial Inequalities

    Homework Statement Solve the following. Express answers in set notation. -2(x-2)(x-4)(x+3)<0 Homework EquationsThe Attempt at a Solution I know my four intervals are x<-3 , -3<x<2 , 2<x<4 , x>4. I thought the answer would be x<-3 and 2<x<4 however the answers are opposite of what I thought...
  5. K

    MHB Range of Values For Inequalities

    Here is a basic inequality question for which I cannot understand the answer: If -1<a-b<10 ,and -3\le b\le1 then what inequality represents the range of values of a2? I plug-in -3 and 1 for b for boundaries and get -4<a<11. Since the boundary is for a2, the range would be 16<a2<121. But why...
  6. T

    Solids of Revolution defined by inequalities

    1. Find the centroids of the solids formed by rotating completely about the x-axis the plane regions defined by the following inequalities: (a) y^2 < 9x, y>0, x<1 (b) xy<4, y>0, 1<x<2 2. I used the equation for solids of revolution: Integral from a to b of (x[f(x)]^2.dx) / Integral from a to b...
  7. F

    System of linear inequalities to find a vector

    Homework Statement Let P be the set of (x,y,z)^t in R^3, which satisfies the following inequalities: -2x+y+z <=4 x-2y+z<=1 2x+2y-z<=5 x>=1 y>=2 z>=3 Homework Equations I want to find the vector in the set with the maximal length. The Attempt at a Solution I have transformed the linear...
  8. F

    Shading in Argand diagrams involving inequalities

    Homework Statement What is difference in shading between Argand diagrams containing inequalities with > and ≥ signs? Example Shade the appropriate region to satisfy the inequality |z|> 5 |z|≥ 5 The Attempt at a Solution I am aware of the fact that both will have circle centered at origin...
  9. E

    Solve Inequalities Problem: x ∈ (-2,-1) ∪ (⅔, -½)

    Homework Statement Find the set of all ##x## for which ##\dfrac{2x}{2x^2 + 5x + 2} > \dfrac{1}{x + 1}## Homework EquationsThe Attempt at a SolutionI'm getting two different sets of answers with two different methods:Method 1-Wrong ##\dfrac{2x}{2x^2 + 5x + 2} > \dfrac{1}{x + 1}####\dfrac{2x^2...
  10. E

    Logic question (handling inequalities in a BASIC compiler)

    Hey everyone, I have a logic question, though I'm not sure if this might belong in the math forum (probably not :P) Anyway, I'm writing a BASIC compiler for the Motorola 68k processor by reverse engineering a dead project/compiler (with permission from the author as he's abandoned it years...
  11. M

    Intro Math What is a good book for inequalities?

    My goal is to master inequalities so that I can have a deep understanding of a book like the Cauchy -Schwartz Master Class by Steele. Right now, that book is too difficult for me. I want to work upto that level and have good intuition about inequalities. Are there any good books where I can hone...
  12. P

    Is this statement for proving inequalities true?

    Hello! What I'm wondering is if you want to prove an inequality, let's say ##a<b## and you already know that ##a>c## is true. If you are able to prove that ##c<b## is true, would that go on to imply that ##a<b## is true also? If this is correct, is it known as a theorem? Thank you!
  13. J

    Proving inequalities with logarithm

    I need to prove: (n+1)*(log(n+1)-log(n) > 1 for all n > 0. I have tried exponentiating it and I got ( (n+1)/n )^(n+1) < e. And from there I couldn't go any farther, but I do know that it is true by just looking at its graph. Could anybody help me please?
  14. lep11

    Is Bernoulli's Inequality Applicable to Prove These Inequalities?

    Homework Statement Prove that a.) (1-(1/n2))n > 1- 1/n b.) (1+ 1/(n-1))n-1 < (1 + 1/n)n when n=2,3,4,5,... Homework Equations [/B] Bernoulli's inequality (1+x)n ≥ 1+nx, when x ≥-1 and n=2,3,4,5,... (1+x)n >1+nx, when x ≥-1, x≠0 and n=2,3,4,5,..The Attempt at a Solution a.)[/B] I applied...
  15. toforfiltum

    Inequalities of negative arguments in complex numbers

    Homework Statement Arg z≤ -π /4 Homework EquationsThe Attempt at a Solution I'm confused whether the answer to that would be more than -45° or less. Should the approach to arguments be the same as in negative numbers?
  16. W

    Cantelli's Inequality and Chebyshev's Inequality

    Homework Statement The number of customers visiting a store during a day is a random variable with mean EX=100and variance Var(X)=225. Using Chebyshev's inequality, find an upper bound for having more than 120 or less than 80customers in a day. That is, find an upper bound on P(X≤80 or X≥120)...
  17. W

    Markov's Inequality for Geometric Distribution.

    Homework Statement Let X∼Geometric(p). Using Markov's inequality find an upper bound for P(X≥a), for a positive integer a. Compare the upper bound with the real value of P(X≥a). Then, using Chebyshev's inequality, find an upper bound for P(|X - EX| ≥ b). Homework Equations P(X≥a) ≤ Ex / a...
  18. EternusVia

    Solving Simultaneous Inequalities

    Homework Statement [/B] I am trying to solve the simultaneous inequalities (1) and (2) shown in the following image. The solution is provided, but I'm not sure how they solved for it. [PLAIN]http:// Homework Equations N/A The Attempt at a Solution [/B] I tried to solve this set of...
  19. J

    Violation of Bell inequalities for classical fields?

    There is a recent article (Optics July 2015) claiming violation of Bell inequalities for classical fields: "Shifting the quantum-classical boundary: theory and experiment for statistically classical optical fields" https://www.osapublishing.org/optica/abstract.cfm?URI=optica-2-7-611...
  20. C

    Inequalities in Normal Distributions

    Homework Statement How does P(-1<Z<1) equal to 1-2P(Z>1)? (So you can find the values on the Normal Distribution Table) Homework EquationsThe Attempt at a Solution I tried P(-1+1<Z+1<1+1) but ended up with P(1<Z+1<2).
  21. yango_17

    Sketching solids given spherical coordinate inequalities

    Homework Statement Sketch the solid whose spherical coordinates (ρ, φ, θ): 0≤ρ≤1, 0≤φ≤(pi/2) Homework EquationsThe Attempt at a Solution I was thinking that since ρ represented the distance from the point of the origin and φ represented the angle between the positive z-axis and the ray through...
  22. zonde

    Can we violate Bell inequalities by giving up CFD?

    I quoted these post from other thread. I don't want to distract discussion in other thread so I'm starting a new one about statements in these posts. Basically the question is if we can violate Bell inequalities by two separated but correlated systems that can be as non-classical as we like (as...
  23. N

    Relation between inequalities for first and second derivatives

    Hi, If f'(x) >= f'(y) can we say that f''(x) >= f''(y) also holds ? And if yes under which conditions ? Thanks
  24. Cosmophile

    Intervals of increasing/decreasing Using Inequalities

    Homework Statement [/B] Identify the open intervals on which the function ##f(x) = 12x-x^3## is increasing or decreasing Homework Equations [/B] ##f(x)=12x-x^3## ##\frac {df}{dx} = 12-3x^2 = -3(x^2 - 4)## The Attempt at a Solution [/B] I'm reading out of two textbooks. One is a...
  25. L

    Inequalities. Special relativity.

    Lorentz transformation. Time separation between two events in system S and system S' is given by Lorentz transformations \Delta t'=\frac{\Delta t-\frac{u \Delta x}{c^2}}{\sqrt{1-\frac{u^2}{c^2}}} If event 2 is caused by event 1 in system S then ##\Delta t=t_2-t_1##. But it is possible to choose...
  26. P

    Binney's interpretation of Violation of Bell Inequalities

    Although he is primarily an astrophysicist, Dirac medal-winning Oxford Professor James Binney has taught a Quantum Physics course to second-year students at the university for years. A series of 27 of his lectures for the course is featured on the university's official website. Binney's take on...
  27. 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...
  28. retrostate

    Liouville's Theorem: Prove f is Constant

    Homework Statement Show that if f is an entire function that satisfies |1000i + f(z)| ≥ 1000, for all z ∈ C, then f is constant. Homework Equations (Hint: Consider the function g(z) = 1000/1000i+f(z) , and apply Liouville’s Theorem.) The Attempt at a Solution Ok, so I assume that as f is...
  29. A

    MHB Represent the following inequalities on a single graph

    3x+4y\le12 3x+y\ge3 y\ge-1 I understand the how to plot these on a graph, just not sure how to solve these inequalities! Do you have to solve for x or y?
  30. ubergewehr273

    Solving Inequalities with Exponents: Maximizing x

    Homework Statement 81^5>32^x Find the maximum value of x in order to satisfy the inequality. Homework Equations Inequalities, indices The Attempt at a Solution Try to make the bases on both sides of the inequality same.
  31. K

    Solving Complex Number Inequalities

    Homework Statement The Attempt at a Solution -1 < (z-w) /(1-z*w) < 1 [/B] Hi can give clue. I am clueless
  32. 3

    Need help with complex number inequalities?

    Hi! At university I have got a problem set with lots of inequalities. Unfortunately there are no explanations given how to do them. In Highschool we only did very easy inequalities. Therefore I am looking for a resource for inequalities. Especially for more difficult inequalities like $$ 1...
  33. J

    Inequalities in Force of Gravitation between Three Bodies

    Homework Statement Given that the force of gravitation between Planet A (the one in the left side of the drawing), Fa=3000/da2 and the force of gravitation between Planet B and the rocket, Fb= 6000/ db2. Assuming that the three bodies involved is in stationary. What are the distances (ranges)...
  34. A

    MHB How do you solve and plot inequalities with multiple variables?

    I have the inequalities 2<x<6,\quad 1<y<5,\quad y-2\le2x, \quad-2y\ge8-4x I have to solve these and plot it in a graph and show the region where they satisfy. I understand you have to find the common area and shade it. How do you find the points to plot for 2<x<6\quad and\quad 1<y<5 I think I...
  35. E

    MHB Solving Polynomial Inequalities

    Solve the following inequality: 6e) $(x - 3)(x + 1) + (x - 3)(x + 2) \ge 0$ So, I created an interval table with the zeros x-3, x+1, x-3 and x+2 but I keep getting the wrong answer. Could someone help? (this is grade 12 math - so please don't be too complicated). Thanks.
  36. Dethrone

    MHB Solving Inequalities with Absolute Values

    1. if $|x-2|<A$, then $|2x-4|<3$ My steps: $$|2x-4|<3$$ $$2|x-2|<3$$ $$|x-2|<3/2$$ Hence, $A>3/2$, why does the answer say that $A\ge 3/2$? 2. if $|x-a|<5$, then $|2x-3|<A$ No idea how to do this one...I tried to manipulate the right inequality into a form such as $|2x-4|$, but I was...
  37. RJLiberator

    Help me proove absolute value inequalities and Solve an Integral

    1) True or Fale? |a-b| \geq ||a|-|b|| My solution: I broke this up into 4 different cases. 1. a> 0 b>0 2. a<0 b<0 and so on... For each case, I ended up with a more simplified version of the inequality. For instance, in case 1 where I used a<0 and b<0, I ended up with the simplified statement...
  38. H

    Annoying inequalities question

    1.On the same axis sketch the graphs of y = (x-a)^-1 and y = 4|x-a| This part i have completed, the first equation has a horizontal asymptote at x = a, it being rectangular hyperbola. the second equation drawn too. 2. Solve (x-a)^-1 < 4|x-a|, giving your answers in a. Now the second part...
  39. FysixFox

    Solving system of inequalities

    (This isn't homework, so I guess it'd go here...) Okay, so I'm trying to solve a system of equations with a bunch of ranges: (Some number between 1.2 and 2.0) = (Some number between 5.5y and 9.1y) = (Some number between 5.4x and 10x) Where X and Y are ranges made up of two percentages (or...
  40. D

    Inequalities of rational expressions

    referring to the photo attached, can anyone expalin and give suitable numerical example please? i couldn't understand the notes.
  41. C

    Inequalities and Rearranging equations

    So i have an equation to calculate the impossibility of pair production during photon decay into two electrons and I'm having to do some momentum conservation, can't quite do it but a colleague of mine has suggested this which I don't particularly agree with some help would be appreciated. So...
  42. A

    Proving convergence given inequalities of powers

    Homework Statement Show that if a>-1 and b>a+1 then the following integral is convergent: ∫(x^a)/(1+x^b) from 0 to ∞ The Attempt at a Solution x^-1 < x^a < x^a+1 < x^b x^-1/(1+x^b) < x^a/(1+x^b) < x^a+1/(1+x^b) < x^b/(1+x^b) I also know any integral of the form ∫1/x^p...
  43. Quarlep

    Multiplying the two inequalities

    Lets suppose we have two inequalities, First inequality is x-y≤a-b≤x+y Second inequality is t-g≤c-d≤t+g How can I multiply these inequalities Thanks
  44. B

    LCD? Equations and inequalities

    Homework Statement 1/z - 1/2z - 1/5z = 10/(z+1) This is the equation presented right after in the textbook where the author explains how to use the LCD to convert this equation into a more understood linear equation. Homework Equations Here is the example before this equation...
  45. MarkFL

    MHB Compute Area of 2 Simultaneous Inequalities: Don Leon at Yahoo Answers

    Here is the question: I have posted a link there to this thread so the OP can view my work.
  46. M

    Inequalities, trigonometric and x exponent.

    These are the two last problems I'll bother you with for a short while (I love this forum, I'll definitely stay on and hopefully be able to contribute in the future). Homework Statement Problem 1: (##-x^2##-1)sin2x > 0 , xe[0,2\pi] Problem 2: ##2^{-x^2+x+2}## < 4 Homework...
  47. R

    Rectangular function & Inequalities

    Note: I think I solved this while writing this topic, did not want to scrap it! if you think its wrong let me know! I am trying to manipulate the rectangular function with different arguments and came across a confusing one Trying to show: \prod (x^2) = \prod (\frac{x}{\sqrt{2}}) Recall that...
  48. Barioth

    MHB Two inequalities set into one.

    Hi everyone, let's stay I have two inequation set such as: First one is A:= X_1-X_2 \leq 1 X_1 \leq3 X_2 \geq 1 X_1,X_2 \geq 0 Second one is B:= X_1+X_2 \geq 5 X_1\leq5 X_1\geq4 X_2\leq4 X_1,X_2 \geq 0 I had like to write it as a set C := A\oplus B, with C made of linear inequations too. I'm...
  49. LeibnizIsBetter

    MHB Epsilon delta proof of a two-variable limit using inequalities

    I seem to be having trouble with multivariable epsilon-delta limit proofs. I don't have a very good intuition for how \epsilon relates to \delta. For example: Prove \lim_{(x,y) \to (0,0)}\frac{2xy^2}{x^2+y^2} = 0 There are probably many ways to do this, but my teacher does it a certain way...
  50. P

    Solve Inequalities algebraically

    Homework Statement The Attempt at a Solution So when I started this question, I knew that 2r +3 > 0 in order for this whole thing to work so r > -3/2, and I know that if the middle term has to be more than 0, than only one more of the others is going to be negative, for the first...
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