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. Traruh Synred

    A Clifford Algebra and generalizing Dirac equaution

    http://arxiv.org/abs/1001.2485 --- The above paper is about a possible two-time formulation of physics. It is by serious people. To understand it I'm trying to generalized the Dirac eqn. to 3+2 dimensions with signature (++---) I found the following (now closed post) useful...
  2. B

    MHB Linear Algebra Expert Requested For Discussion

    I was wondering if there was anyone comfortable enough about basic to advanced linear algebra concepts who would be willing to participate in a chat/whiteboard based platform to discuss or answer questions concerning such concepts. I need clarification on a few things
  3. terryds

    Algebra problem (x+(1/x) problem)

    Homework Statement If ##a+\frac{1}{a}=\sqrt{3}##, then ##a^{2016} + (\frac{1}{a})^{2016} ## equals A. 0 B. 1 C. √2 D. √3 E. 2 Homework EquationsThe Attempt at a Solution [/B] I find no real solution for a. What I can do is just find a^2 + (1/a)^2 which equals 1, a^4 + (1/a)^4 = -1, a^8 +...
  4. leighflix

    B What use is there for rationalizing denominator?

    I've been learning algebra for the past 2 years (in high school), not once have we ever had to rationalize a denominator in a radical expression. I am now relearning Algebra and Trig., what use is there? I mean, all you're doing is switching the numerator (rational) to the Denominator...
  5. K

    Pauli Equation - Simple operator algebra question

    Homework Statement I am watching a course on Relativistic Quantum Mechanics to freshen up, and I have found to have some issues regarding simple operator algebra. This particular issue on the Pauli Equation (generalization of the Schrodinger equation that includes spin corrections) in an...
  6. Danielm

    Proving Linear Independence and Spanning in Vector Spaces

    Homework Statement Prove the following: Let V be a vector space and assume there is an integer n such that if (v1, . . . , vk) is a linearly independent sequence from V then k ≤ n. Prove is (v1, . . . , vk) is a maximal linearly independent sequence from V then (v1, . . . , vk) spans V and is...
  7. Danielm

    Proof: Linear Dependence of Vectors in a Vector Space

    Homework Statement Prove the following theorem: Let (v1, . . . , vk) be a sequence of vectors from a vector space V . Prove that the sequence if linearly dependent if and only if for some j, 1 ≤ j ≤ k, vj is a linear combination of (v1, . . . , vk) − (vj ). Homework EquationsThe Attempt at a...
  8. S

    MHB Exploring Linear Algebra as a Computer Science Major

    Computer science major here. I recently completed calculus I, II, III. Now I know that I'll probably be required to take linear algebra. So far, I expect to do some Gaussian elimination (assuming I know what a row echelon is). What else should I expect from linear algebra?
  9. E

    Schools Take College Algebra and study for Trigonometry?

    Hello. I am a sophomore and I attend an Early College High school. I am currently in Geometry this year and I will be taking Algebra II during the first half of summer. To account for the second half-credit of Algebra II, I will be taking College Algebra in the second half of summer. Throughout...
  10. ibkev

    Linear Algebra showing a subspace

    I'm having trouble getting started on this one and I'd really appreciate some hints. This question comes from Macdonald's Linear and Geometric Algebra book that I'm using for self study, problem 2.2.4. Homework Statement Let U1 and U2 be subspaces of a vector space V. Let U be the set of all...
  11. G

    Algebraic equation -- six degree polynomial

    Homework Statement Solve the equation for r,r>0,r<R. \frac{-2\pi R^3}{3}-\frac{8\pi r^2\sqrt{R^2-r^2}}{3}+2r^2R+\frac{2\pi}{3}R^2\sqrt{R^2-r^2}=\frac{2\pi R^3}{3} 2. The attempt at a solution After factoring, -2R(2\pi R^2-3r^2)=2\pi\sqrt{R^2-r^2}(4r^2-R^2). After squaring, 64\pi^2...
  12. thegirl

    I Why does cos(phi1- phi 2 +kX)=cos(kx)?

    In the case of two fields interfering with each other when calculating the total electric field, cos (phi1-phi2 + kx) = cos( kx) where kx is the path difference between the two fields. How does cos (phi1-phi2 +kx)=cos(kx) Isit just algebra?
  13. Y

    Linear Algebra - Singular Value Decomposition Problem

    Homework Statement Find the SVD of Homework EquationsThe Attempt at a Solution I'm stuck My question is why in the solution it originally finds u_2=[1/5,-2/5]' but then says u_2=[1/sqrt(5),-2/sqrt(5)]'. I don't see what math was done in the solution to change the denominator from 5...
  14. Kernul

    Solve Boolean Algebra Homework

    Homework Statement Simplify the expression ##cb' + ca'b + cabd + cad'## Homework Equations All the properties of boolean algebra. The Attempt at a Solution Here's how I did it: $$cb' + ca'b + cabd + cad' = $$ $$c(b' + a'b + abd + ad') = $$ $$c(b' + a'b + a(bd + d')) = $$ $$c((a + a')b' + a'b...
  15. xwolfhunter

    B "Neighbor fractions" in Gelfand's Algebra

    I'm reading Gelfand's algebra, and I encountered some wonky stuff that I can't figure out on my own (hence my need for the book in the first place) in problem 42 of the book. Here is an explicit statement of the problem. I thought parts a. and b. were easy, but when it came to part c., I just...
  16. micromass

    Insights How to Self-study Algebra: Linear Algebra - Comments

    micromass submitted a new PF Insights post How to Self-study Algebra: Linear Algebra Continue reading the Original PF Insights Post.
  17. Math Amateur

    I The Tensor Algebra - Cooperstein, Example 10.1

    I am reading Bruce N. Coopersteins book: Advanced Linear Algebra (Second Edition) ... ... I am focused on Section 10.3 The Tensor Algebra ... ... I need help in order to get a basic understanding of Example 10.1 in Section 10.3 ...Example 10.1 plus some preliminary definitions reads as...
  18. Math Amateur

    I The Tensor Algebra - Cooperstein, Defn 10.5

    I am reading Bruce N. Coopersteins book: Advanced Linear Algebra (Second Edition) ... ... I am focused on Section 10.3 The Tensor Algebra ... ... I need help in order to get a basic understanding of Definition 10.5 in Section 10.3 ...Definition 10.5 plus some preliminary definitions reads as...
  19. O

    A Integrating the topics of forms, manifolds, and algebra

    Hello, As you might discern from previous posts, I have been teaching myself: Calculus on manifolds Differential forms Lie Algebra, Group Push forward, pull back. I am an engineer approaching this late in life and with a deficient background in math. It is all coming together and I almost...
  20. smodak

    Linear Algebra Found a real nice free linear algebra book

    https://www.math.ucdavis.edu/~anne/linear_algebra/
  21. smodak

    I Stupid Question about a Notation in Linear algebra

    I know the arrow -> means a map. For example, defines a linear map. But I cannot figure out what does a X mean? I know that above denote a inner product map. whatever is on the left of the : is defined by whatever is on the right. but what is the x symbol? What is the correct way to read...
  22. P

    Linear Algebra -- Projection matrix question

    Homework Statement Let A be an n×n matrix which has the property that A^2 =A. (i) Write down the most general polynomial in AHomework EquationsThe Attempt at a Solution My biggest problem is that I don't even understand what the question is asking Is it just sum (alphaA^n)=0 but A^n=A...
  23. M

    Linear Algebra- Dependent or independent

    Homework Statement Let(v1, v2, v3) be three linearly independent vectors in a vector space V. Is the set {v1-v2, v2-v3, v3-v1} linearly dependent or independent? Homework Equations Linearly independent is when c1v1+c2v2+...+ckvk=0 and c1=c2=...ck=0 The Attempt at a Solution c1(v1-v2)+...
  24. Y

    Linear Algebra - Find Orthogonal Matrix Q that diagonals

    Homework Statement I'm told to find the matrix Q of the matrix A Homework EquationsThe Attempt at a Solution So my problem is that in the answer key they have S = (1/3)... and I have no idea where this 1/3 comes from. I get an equivalent answer for X_1, X_2, and X_3 S = [X_1, X_2, X_3] but...
  25. A

    Linear algebra or intro to programming courses have higher failure rate?

    which has higher failure rate: linear algebra or intro to programming. I understand failure rate might be skewed: math majors, who are gifted and interested in math, are required to take linear algebra but not intro to programming, while CS majors are required to take both. Which class do CS...
  26. V

    What is the common root for two polynomial equations with a shared coefficient?

    Homework Statement [/B] Th value of 'a' for which the equation x3+ax+1=0 and x4+ax+1=0 have a common root is?Homework EquationsThe Attempt at a Solution i initially thought of subtracting both the equations and then finding x and substituting back in the equation but it did not work.
  27. Biker

    B Algebra question -- Solving 2 simultaneous equations....

    It is a bit of a long question about series, But what is important is this... a+ 2c = 3b (3b-2)^2 = 2a * (4c-2) It is asking for the ratio c to a It have tried a lot of ways. I always end up with this. (Note maybe I not noticing a mistake, Can just anyone confirm that this is solvable? )...
  28. joe_cool2

    Linear Algebra - Gram-Schmidt Process

    Homework Statement Let R2 have the Euclidean inner product and use the Gram-Schmidt process to transform the basis {u1,u2} into an orthonormal basis. u1 = (1,-3) u2 = (2,2) Homework Equations Gram-Schmidt process: \\v_1 = u_1 \\v_2= u_2 - \frac{\left ( \left \langle u_2, v_1\right \rangle...
  29. binbagsss

    I Basic question, harmonic coordinate condition algebra

    where ##□=\nabla^{\mu}\nabla_{\mu}## is the covariant D'Alembertian. ##□x^{\mu}=0## ##g^{\rho\sigma}\partial_{\rho}\partial_{\sigma}x^{\mu}-g^{\rho\sigma}T^{\lambda}_{\rho\sigma}\partial_{\lambda}x^{\mu}=0## So this line is fine by subbing in the covariant derivative definition and lowering...
  30. Y

    Engineering Linear Algebra - Analysis of purely resistive DC circuit

    Homework Statement I'm trying to solve this circuit when I try to simulate and run a dc sweep i get that it can't be solved. When I try to find the answer using linear algebra I get this answer after I throw it into MATLAB with the warning “[w]arning: Matrix is close to singular or...
  31. Y

    Linear Algebra - Elimination Matrix when Permutation Needed

    Homework Statement I feel like I should know the answer to this, so I believe this to be an easy question. Say have matrix A, and I store the elimination matrices E_1,1 E_2,1 etc. and somewhere in the elimination process I have to use a permutation matrix to swap rows. My question is when I...
  32. G

    I What is the rank of the SU(2)xSU(2) algebra?

    I am reading in my group theory book the well known commutation relations of the Lie algebra of SO(3), i.e. [J,J]=i\epsilon J. What I don't understand is the statement that "from the relations we can infer that the algebra has rank 1". Any ideas?
  33. Y

    Linear Algebra - Gram Schmidt & Normalization - Error in Sol

    Homework Statement So I think I found an error in the solution were it attempts to find q_2^ I'm asked find the orthornomal basis for the column space of matrix A. Homework EquationsThe Attempt at a Solution [/B] My question is in what it puts for q_2^ A_2 = [4/3 4/3 -2/3]^T ||A_2|| =...
  34. squelch

    Vector Algebra: Finding a parallel vector

    Homework Statement A line is given by the equation ##x + 2y - 3z = 7##. Find any vector in the direction parallel to this line in the Cartesian coordinate system. Homework Equations I imagine that there are some fundamental relationships I am missing here that would make this more...
  35. Y

    Linear Algebra - Projection of Vector

    Homework Statement I feel like this is a easy question but it seems the answer key doesn't seem to be right. So say I have 2 vectors and I'm trying to find the projection of vector u perpendicular to the vector v Homework EquationsThe Attempt at a Solution So I don't remember doing...
  36. Schwarzschild90

    Evaluating U(l) with Applied Linear Algebra: A Gambler's Demise

    Homework Statement I ask for help in solving the exercises in this project on applied linear algebra. The problem outlined in the project is one in which we are tasked with modeling the demise of a gambler. I need help solving exercise 1 (in red) on page 6. I have pasted the exercise text...
  37. Y

    Linear Algebra - Solving AC RLC circuit

    Homework Statement So yeah I'm doing a project were I get to create a problem. I would like to learn how to solve a AC RLC circuit using linear algebra. I'm trying to find all of the currents on the edges of the graphs and find all of the voltages at the nodes connecting the edges. I don't...
  38. Z

    Linear equations algebra based problem

    Homework Statement I got following Question from a book: I am doing it using a different method but my answer is wrong. Can somebody please guide me, what is the problem with it?? The question is:In 1999, Diana read 10 English books and 7 French books. In 2000, she read twice as many French...
  39. P

    Simplifying output for a XOR gate using Boolean Algebra

    Homework Statement I'm trying to show that the output of this XOR circuit is ##F=A'B+AB'##, Homework Equations ##(A+B)'=A'\cdot B'## ##(A\cdot B)'=A'+B'## The Attempt at a Solution From the gates the output is ##[(A\cdot B)+(A+B)']'##, using De Morgan's laws this becomes ##[(A\cdot...
  40. CynicusRex

    Studying Guidelines to studying linear algebra and statistics.

    I'll try to be concise. I've been out of math for years and never truly learned to understand it. Until now. I want to put the growth mindset theory to the test and see if I can handle physics (or any STEM field) on a university difficulty. To verify if I'm up to it and even have the slightest...
  41. F

    So what am I supposed to learn in linear algebra

    I am self teaching the subject but I am unsure of what is the whole point and picture
  42. Ismail Siddiqui

    [Linear Algebra] Conjugate Transpose of a Matrix and vectors in ℂ

    Homework Statement Let A be an n x n matrix, and let v, w ∈ ℂn. Prove that Av ⋅ w = v ⋅ A†w Homework Equations † = conjugate transpose ⋅ = dot product * = conjugate T = transpose (AB)-1 = B-1A-1 (AB)-1 = BTAT (AB)* = A*B* A† = (AT)* Definitions of Unitary and Hermitian Matrices Complex Mod...
  43. L

    Algebra Books that mix modern physics with algebra and geometry

    Hi I'm an advanced undergraduate physics student and I'm currently searching books for my career project. The topic I selected is titled: Algebra and geometry in modern physics. So I'm currently looking for books that cover modern aspects of physics in a more mathematical approx. In specific I'm...
  44. S

    Students failing their first course of Algebra

    This article sounds or reads like the same old problem: http://news.yahoo.com/algebra-unnecessary-stumbling-block-us-schools-170616735.html Why should that be? Students fail algebra 1 either because of lack of effort, lack of motivation, or, if for any student the course is difficult, the...
  45. B

    Pre-Cal to Calc 1: Which Option is Best?

    Hi everyone, I am new here. I know this has been asked before so forgive me, but ima ask again. :) So I'm n pre cal right now and it's going fairly well. I think I'll pass with a B. Next I need to take calculus 1..then later calc 2. So I have 2 options. 1. I can take calculus 1 this summer. I...
  46. O

    Suggestions for algebra text for 14 year old

    Hello Could someone suggest a good book for my son to read to learn algebra? I look in the bookstores and the books titled "Algebra..." all involve equations and unknowns and arithmetic manipulations and train or work problems (2 farmers plow three fields in one day, etc) I am interested in...
  47. G

    Calc Physics vs Algebra Physics

    Does taking calculus based physics make it fun and more understandable, compared to algebra based physics? It seems like the algebra-based physics you don't go in-depth.
  48. N

    How many cats remained after women in West Cornwall lost sacks and cats?

    Homework Statement In West Cornwall, I met w women each carrying s sacks, each containing c cats. However, a third of the women then lost half their sacks, and the remaining women lost half their cats from a third of their sacks. How many cats remained, it terms of w, s and c?2. The attempt at...
  49. O

    B Need help with algebra in proving kinetic energy is not conserved

    I'm trying to prove that kinetic energy is not conserved in inelastic collisions using the conservation of momentum. This is the set-up. An object A of momentum ##{m_1}{v_1}## collides inelastically with object B of momentum ##{m_2}{v_2}## using momentum conservation ##P_i = P_f## {m_1}{v_1} +...
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