What is Algebra: Definition and 999 Discussions

Algebra (from Arabic: الجبر‎, romanized: al-jabr, lit. 'reunion of broken parts, bonesetting') is one of the broad areas of mathematics, together with number theory, geometry and analysis. In its most general form, algebra is the study of mathematical symbols and the rules for manipulating these symbols; it is a unifying thread of almost all of mathematics. It includes everything from elementary equation solving to the study of abstractions such as groups, rings, and fields. The more basic parts of algebra are called elementary algebra; the more abstract parts are called abstract algebra or modern algebra. Elementary algebra is generally considered to be essential for any study of mathematics, science, or engineering, as well as such applications as medicine and economics. Abstract algebra is a major area in advanced mathematics, studied primarily by professional mathematicians.
Elementary algebra differs from arithmetic in the use of abstractions, such as using letters to stand for numbers that are either unknown or allowed to take on many values. For example, in



x
+
2
=
5


{\displaystyle x+2=5}
the letter



x


{\displaystyle x}
is an unknown, but applying additive inverses can reveal its value:



x
=
3


{\displaystyle x=3}
. Algebra gives methods for writing formulas and solving equations that are much clearer and easier than the older method of writing everything out in words.
The word algebra is also used in certain specialized ways. A special kind of mathematical object in abstract algebra is called an "algebra", and the word is used, for example, in the phrases linear algebra and algebraic topology.
A mathematician who does research in algebra is called an algebraist.

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  1. F

    Which sigma algebra is this function a measure of?

    Suppose ##\nu## is a measure on some ##\sigma##-algebra ##\mathcal{A}##. Then we must have for all ##A \in \mathcal{A}## either ##A## or ##A^c## is finite, but not both. Because otherwise ##\nu(A)## is undefined or not well defined. I've verified that ##\lbrace \emptyset, X \rbrace## and...
  2. Adesh

    I What is meant by "convergent just preceding ##\frac{a}{b}##" ?

    Continued Fractions are themselves quite odd to learn and see in modern Algebra courses. The convergents are the numbers that we get when stop the division process at any stage. I know the laws related to convergents, let ##p_n## denote the numerator of ##n##th convergent and ##q_n## the...
  3. MidgetDwarf

    I Explanation of a Line of a proof in Axler Linear Algebra Done Right 3r

    ∈Was wondering if anyone here could help me with an explanation as to how Axler arrived at a particular step in a proof. These are the relevant definitions listed in the book: Definition of Matrix of a Linear Map, M(T): Suppose ##T∈L(V,W)## and ##v_1,...,v_n## is a basis of V and ##w_1...
  4. A

    A Algebra of divergent integrals

    Hello, guys! I would like to know your opinion and discuss this extension of real numbers: https://mathoverflow.net/questions/115743/an-algebra-of-integrals/342651#342651 In essence, it extends real numbers with entities that correspond to divergent integrals and series. By adding the rules...
  5. S

    Algebra Book on Lie algebra & Lie groups for advanced math undergrad

    Posting for my son (who does not have an account here): He's a sophomore math major in college and is looking for a good book on Lie algebra and Lie Groups that he can study over the summer. He wants mathematical rigor, but he is thinking of grad school in theoretical physics, so he also wants...
  6. M

    Comp Sci Proving a Logic Rule with Boolean Algebra: Step-by-Step Guide

    Hello, can anyone help how i prove this logic rule? I am not sure whether i have to draw a digital circuit or something. if someone could help me solve it showing the steps they took i'd appreciate thanks
  7. K

    MHB Algebra word problem solve for x

    Help me solve this word problem please & explain how you did it-thanks so much, I 'm tearing my hair out. Jason purchased a can of tomato sauce and three pounds of apples for $\$7.05$. Gina purchased a can of tomato sauce and 5 pounds of apples for $\$11.35$. What is the price of the tomato...
  8. A

    MHB Introduction to linear algebra

    prove that $2+8{\sqrt{-5}}$ is unit and irreducible or not in $\mathbb Z+\mathbb Z{\sqrt{-5}}$.
  9. A

    MHB Introduction to linear algebra

    prove that u(z+zw)={+1,-1,+w,-w,+w^2,-w^2}
  10. SpaceMonkeyCaln

    [Linear Algebra] Matrix Transformations

    Evening, The reason for this post is because as the title suggests, I have a question concerning matrix transformation. These are essentially test prep problems and I am quite stuck to be honest. Here are the [questions](https://prnt.sc/riq7m0) and here are the...
  11. M

    I Relationship between a Lie group such as So(3) and its Lie algebra

    I am just starting a QM course. I hope these are reasonable questions. I have been given my first assignment. I can answer the questions so far but I do not really understand what's going on. These questions are all about so(N) groups, Pauli matrices, Lie brackets, generators and their Lie...
  12. Mondayman

    Linear Algebra What are some recommended second texts for self-studying linear algebra?

    Hello folks, I am currently finishing up a class on linear algebra, covering vector spaces, bases and dimension, geometry of n-dimensional space, linear transformations and systems of linear equations. I am only getting accustomed to proof writing for the first time in this course. However, I...
  13. S

    Integration of an exponential and algebra

    ##\int \frac{e^x (2-x^2)}{(1-x) \sqrt{1-x^2}} dx## I tried using substitution x = sin θ but still can not solve it. I guess I have to get rid the term ex but do not know how Thanks
  14. V

    I Group Theory sub algebra of unitary group of U(6) group.

    three sub algebra of Unitary group (6) as 1. U(5) . 2. SU(3) 3. O(6) here the three chains in attachment is attached. I want to know how these chains are understands in group theory.
  15. P

    A Questions about representation theory of Lie algebra

    I have confusions about representation theory. In the following questions, I will try to express it as best as possible. For this thread say representation is given as ρ: L → GL(V) where L is the Lie group(or symmetry group for a physicist) GL(V) is the general linear...
  16. JD_PM

    What are the coordinates of the upper cylinder? (and some algebra)

    I was solving a problem and got stuck in two aspects: 1) Geometric issue. Alright, I understand that the coordinates of the lower cylinder are $$( -R \theta_1, R)$$ The coordinates of the upper cylinder are: $$( x_1 + 2R \sin \theta, 3R - 2(R-\cos \theta))$$ I get that the ##x##...
  17. M

    Help with a Linear Algebra problem please

    For the following statement: V = R ≥ 1; x ⊕ y = max (x,y), with z = 1 My attempt is as follows: Should R3 be z ⊕ (x ⊕ y)? I am confused at to the notation of this rule. Moreover, I am struggling to find examples and answers of such problems in linear algebra online. Should I always view such...
  18. Avatrin

    3D geometry exercises with linear algebra

    Hi I have noticed that while I have the grasp of the theoretical underpinnings of linear algebra, I need work on applying it to geometric problems (think computer vision and rigid body motion). So, I am looking for a book that allows me to practice 3D geometry problems. Is there any obvious...
  19. BadgerBadger92

    Best Intermediate Algebra textbooks?

    I want to teach myself math, and am trying to start with intermediate algebra. What are some of the best textbooks on this subject, especially for someone trying to learn this without a class?
  20. L

    A Unitary representations of Lie group from Lie algebra

    In Quantum Mechanics, by Wigner's theorem, a symmetry can be represented either by a unitary linear or antiunitary antilinear operator on the Hilbert space of states ##\cal H##. If ##G## is then a Lie group of symmetries, for each ##T\in G## we have some ##U(T)## acting on the Hilbert space and...
  21. Y

    Deriving commutator of operators in Lorentz algebra

    Li=1/2*∈ijkJjk, Ki=J0i,where J satisfy the Lorentz commutation relation. [Li,Lj]=i/4*∈iab∈jcd(gbcJad-gacJbd-gbdJac+gadJbc) How can I obtain [Li,Lj]=i∈ijkLk from it?
  22. A

    Matrix which reverses Gram-Schmidt - Linear Algebra

    My idea was to write out the formulas for the orthogonal q vectors in terms of the input vectors using the basics of gram-schmidt. Then, I would rewrite those equations suhc that the a vectors were written in terms of the q vectors. And then, try to find some matrix which would capture the...
  23. L

    MHB Introductory Algebra Percentage Word Problem

    The problem as given in the book: The price of a dress is marked down 20% on May 1. On May 25th the reduced price is marked down an additional 15% to \$51. (a) What percent of the original price is the final sale price? (b) "What is the original price? All I could think was trying to work...
  24. B

    A Calculating Nabla w V in General Relativity

    in the language of general relativity,we know that we can write $$\nabla_{V}W $$ in this form such that: $$\nabla_{V}W = = w^i d ( V^j e_j)/du^i = w^j e^i (V^j e_j ) = W( V)$$ where $$w^i * d/ (du^i) =W$$ will act on the vector V where $$W = w^i d( ) /du^i $$ and W is a vector as a...
  25. S

    I A matter of style? Algebra, Arithmetic, Variables

    When people graduate and have their degrees in engineering or physics or mathematics or what they may have done, some of these people will use some mathematics, very often which is some-what complicated (or not) arithmetic. Why will some people choose to strictly avoid using variables in the...
  26. M

    Will an algebra and trig texbook be sufficient preparation for calc?

    I took Algebra I, II, and precalculus in high school, but I graduated high school some time ago and would like to prepare for calculus before I go back to school. My question is if a textbook that covers both Algebra and Trigonometry will sufficiently prepare me for calculus (I plan on taking...
  27. P

    MHB Please help with bool algebra and logic things

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  28. dsilvas

    Algebra: How do I derive this equation given two other equations?

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  29. caters

    What is the ratio after 1 month given certain conditions?

    So this question is a math question having to do with me calculating the rate of population growth starting from a population of 100,000. I have already gotten the first 3 steps done (sex ratio, ratio of cycle time, and pregnancy ratio) after a week among those in the fertile timeframe...
  30. garthenar

    Solving for a neutralizing B0 in a Thomson Cathode Ray (Algebra?)

    I've attached a picture from the problem, the given equations, and my work so far. I knew I had a problem when My units wouldn't check out. This should just be simple algebra but It's not working. Please help me to understand what I am doing wrong.
  31. PeroK

    I Fundamental Theorem of Algebra: Proof

    I found this video showing an elementary proof of the FTA.
  32. R

    Engineering Prove using Boolean algebra that two expressions are equivalent

    Can anyone tell me if I'm doing this right so far? My question really is... does this mean that the next step for me is to expand the last statement shown?Asking because that seems like a lot of work.
  33. Jason Bennett

    Lorentz algebra elements in an operator representation

    1) Likely an Einstein summation confusion. Consider Lorentz transformation's defined in the following matter: Please see image [2] below. I aim to consider the product L^0{}_0(\Lambda_1\Lambda_2). Consider the following notation L^\mu{}_\nu(\Lambda_i) = L_i{}^\mu{}_\nu. How then, does...
  34. mdb71

    A Smart Algebra of Exp. on Pg 191 of Peskin & Schroeder

    Hi all, I have a problem working out the algebra of the following expression in Peskin & Schroeder in a smart way to give the result. It is on page 191, regarding the numerator of the vertex correction function. We want to get from the LHS to the RHS of the following expression...
  35. R

    MHB High school simple algebra word problem

    The 100W light bulb (cost 0.60 dollars) is not going to be used anymore and is being replaced with the 20W (cost 3 dollars) low energy light bulb. If electricity is charged at $0.15 per kWh, for how many hours must the low energy bulb be used in order for the lower cost of running it to exactly...
  36. T

    Simplifying a matrix algebra equation (revised)

    I have a matrix equation (left side) that needs to be formatted into another form (right side). I've simplified the left side as much as I could but can't seem to get it to the match the right side. I am unsure if my matrix algebra skills are lacking or if I somehow messed up the starting...
  37. Hiero

    I Geometric Algebra: Rejection of one blade in another

    Let the (multi-vector valued) “inner product” between a j-vector U and a k-vector B be defined as the (k-j) grade part of the geometric product UB, (a.k.a. “left contraction”) that is, $$U\cdot B := <UB>_{k-j}$$ (0 when j > k) as is done in Alan Macdonald’s book “Linear and Geometric Algebra.”...
  38. Abhishek11235

    I Condition for delta operator and total time differential to commute

    While deriving continuity equation in Fluid mechanics, our professor switched the order of taking total time derivative and then applying delta operator to the function without stating any condition to do so(Of course I know it is Physics which alows you to do so) . So,I began to think...
  39. V

    MHB Solving Algebra equation 3x=15

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  40. C

    Schools Where should I take my calculus and linear algebra online?

    Has anyone taken these two courses online in a self-paced course for credit? If so, where and how was it in terms of quality? How about price? Opinions/thoughts are much appreciated. I'm working and the closest community college is a commute away, so that's out. I'm finding $1100-3000~ for...
  41. U

    Motorboat Ques: Gelfand Algebra 131 | Hints to Help

    I am struggling on how to approach this problem. Hints would help greatly. This is also from Gelfand's Algebra problem 131
  42. Eclair_de_XII

    If you were a linear algebra teacher, would you dock points for this?

    Let's say you were proctoring some test that required proofs of Jordan canonical forms and rational canonical forms. Would you dock points from a lazy student abbreviating the former as "J-canonical forms" and the latter as "##\mathbb{Q}##-canonical forms" in their proofs?
  43. F

    B Why is the distributive law correct in algebra, like in arithmetic?

    When they give reason for multiplication the negative numbers leading to positive number, they base on distribute law.But why the distribute law in algebra is correct like in arithmetic?(e.g why -5(8-6)=-5.8+-5.-6?).In abstract algebra they use distribute law as axiom.But in elementary algebra...
  44. G

    MHB Solve linear algebra equation 2x – 1 = 9 – 3x

    Hi, Could someone help me with this question: 2x – 1 = 9 – 3x Thank you in advance!
  45. W

    Equivalent representations for Dirac algebra

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  46. RikaWolf

    I Linear Algebra - Inner Product problem

    I need help to know if I'm on the right track: Prove/Disprove the following: Let u ∈ V . If (u, v) = 0 for every v ∈ V such that v ≠ u, then u = 0. (V is a vector-space) I think I need to disprove by using v = 0, however I'm not sure.
  47. R

    Verify the equation 2y+30=8y

    8y-2y=6y 6 y+30 6y/6=30/6 Y=5 Now how can I verify this equation?
  48. R

    Algebra: simplify 3m+2k+m

    3m+m=4m 4m +2k =6mk Is this correct, help please if not correct Thanks
  49. F

    Master Algebra Revision with Exam Tips & Methods | Boost Your Summer Exam Prep

    have a Summer Exam , at the begging of next week on all topics that we have done , so I decided to do Algebra , but I forgot have to do it , because it was a while ago, can anyone show me the method again please to memorize. Thanks in advance . Workings : add 4x+5=9 3x+6=9 9/3 =3/3 3x=3
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