Algebra Definition and 999 Threads

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.

View More On Wikipedia.org
  1. caters

    Solve for unknown radius without trig

    Homework Statement What is the next radius outwards of this Apollonian gasket? R = radius of outer circle = 5 r1 = radius of largest inner circle = 3 r2 = radius of second largest inner circle = 1 a = unknown radius Homework Equations C = 2πr A = πr2 d = 2r The Attempt at a Solution Make a...
  2. Math Amateur

    MHB Centre of an Algebra .... and Central Algebras ....

    I am reading Matej Bresar's book, "Introduction to Noncommutative Algebra" and am currently focussed on Chapter 1: Finite Dimensional Division Algebras ... ... I need help with some remarks of Bresar on the centre of an algebra ... Commencing a section on Central Algebras, Bresar...
  3. Math Amateur

    I Centre of an Algebra .... and Central Algebras ....

    I am reading Matej Bresar's book, "Introduction to Noncommutative Algebra" and am currently focussed on Chapter 1: Finite Dimensional Division Algebras ... ... I need help with some remarks of Bresar on the centre of an algebra ... Commencing a section on Central Algebras, Bresar writes the...
  4. binbagsss

    I QFT Feynman Propagator Algebra

    I am wanting to get the expression up to ##O(\epsilon^{2}) ## : To show that ##\frac{1}{2w_{k}} (\frac{1}{w_{k}-k_{0}-i\epsilon} + \frac{1}{w_{k}+k_{0}-i\epsilon})## ##=## ## \frac{1}{k_{v}k^{v} + m^{2} - i\epsilon}##, [2] where ##w_{k}^{2}=k^{2}+m^{2}##, ##k## the variable, and (this seemed...
  5. Unteroffizier

    Algebra II, Rational Expressions & Square Roots problems

    Problem 1 Simplify/solve: 2*81/2-7*181/2+5*721/2-50 Attempt at solution: a1/2=√a ⇒ 2*√8 - 7*√18 + 5*√72 - 50 = 2√8 - 7√18 + 5√72 - 50 = ? Do not know how to proceed beyond this point. Have experimented with little luck. Problem 2 Simplify/solve: a-1(1+1/a2)-1/2 * (1+a2)1/2 Attempt at...
  6. binbagsss

    Discriminant function and paritition function - modular forms - algebra really

    Homework Statement I am wanting to show that ##\Delta (t) = 1/q (\sum\limits^{\infty}_{n=0} p(n)q^{n})^{24} ## where ##\Delta (q) = q \Pi^{\infty}_{n=1} (1-q^{n})^{24} ## is the discriminant function and ##p(n)## is the partition function, Homework Equations Euler's result that : ##...
  7. MrsM

    Linear Algebra: characteristic polynomials and trace

    The question is : Is it true that two matrices with the same characteristic polynomials have the same trace? I know that similar matrices have the same trace because they share the same eigenvalues, and I know that if two matrices have the same eigenvalues, they have the same trace. But I am...
  8. Math Amateur

    MHB Books on Noncommutative Algebra

    I would be interested to know from MHB readers, of any books on Noncommutative Algebra you have a high opinion of ... ... especially those that are at the advanced undergraduate and beginning graduate level ...The books I have on this topic are as follows: Introduction to Noncommutative Algebra...
  9. doktorwho

    Can you help me solve this Boolean algebra problem?

    Homework Statement Prove that $$(\bar{a} + b)(b+c) + a\bar{b}$$ where ##a,b## can be from the set ##B\in\{0, 1\}## equals $$a+b+c$$ Homework Equations Rules of Boolean Algebra 3. The Attempt at a Solution [/B] My attempt: ##\bar{a}b + \bar{a}c + bb + bc + a\bar{b}## ##b(\bar{a} + 1+c) +...
  10. C

    Linear Algebra Good reading on Applied Linear Algebra?

    I've been studying graduate level Linear Algebra from Steven Roman's Advanced Linear Algebra (Springer, GTM). It is a terrific book, but many of the concepts are extremely abstract so that I find it difficult to retain what I've learned. Can anyone point me to some books/reading on the...
  11. anemone

    MHB Solve Algebra Challenge: $(x+1)(y+1)/(x+y)+\cdots

    Given that $x,\,y$ and $z$ are non-zero real numbers such that $x + y + z = 3$ and $xy + yz + zx = −1$. Evaluate \frac{(x + 1)(y + 1)}{x + y}+ \frac{(y + 1)(z + 1)}{y + z}+ \frac{(z + 1)(x + 1)}{z + x}.
  12. E

    Courses What Math Course is Best Paired with Linear Algebra?

    I'm currently an applied math major. I'm creating a schedule for my next semester and I have the choice to take either complex variables or vector analysis with linear algebra and a college geometry course(elective of choice), but I don't know which pairing will be less stressful. I am currently...
  13. A

    Need to be sure of this boolean algebra problem's solution

    Homework Statement Express the function Y= (abd + c)' + ((acd)'+(b)')' as the complete disjunctive normal form: 2.1 by applying Boole's theorerm, Homework EquationsThe Attempt at a Solution I separated the equations to two terms (T1,T2) T1= (abd + c)' T2=((acd)'+(b)')' T1= (abd+c)'...
  14. A

    MHB Algebra help - a race around a regular polygon

    Bert and Ernie are running around a regular polygon with x sides, all of length 12m. They start from the same point and run in opposite directions. If Bert is twice as fast as Ernie, how far will Ernie have traveled when they meet?
  15. Matejxx1

    Vector algebra (proving you have a parallelogram by using vectors)

    Homework Statement 23. In a ABCD quadrilateral let P,Q,R,S be midpoints of sides AB,BC,CD and DA. Let X be the intersection of BR and DQ, and let Y be the intersection of BS and DP. If ##\vec{BX}=\vec{YD} ## show that ABCD is a parallelogram . Homework Equations ## (\vec{a}\cdot\vec{b})=0##...
  16. I

    MHB Solve Algebra Question Easily: 34

    I know that I can use guess and check, but I was wondering if there was an easier way? I got 34
  17. S

    I Solve Lie Algebra Easily: No Math Theory Needed

    Hello! Is there any rule to do sums and products like the one in the attached picture (Lie.png) without going through all the math theory behind? I understand the first (product) and last (sum) terms, but I am not sure I understand how you go from one to another. Thank you!
  18. S

    I Lie Algebra in Particle Physics simplified

    Hello! Is there any rule to do sums and products like the one in the attached picture (Lie.png) without going through all the math theory behind? I understand the first (product) and last (sum) terms, but I am not sure I understand how you go from one to another. Thank you!
  19. Cocoleia

    Stuck with this non-trivial algebra, solving for x

    Homework Statement I am trying to solve for x in this equation: Homework EquationsThe Attempt at a Solution I tried solving it like a quadratic equation. This is the most simplified I could get it. Can someone please help me find a simpler expression
  20. binbagsss

    Geometric series algebra / exponential/ 2 summations

    Homework Statement I want to show that ## \sum\limits_{n=1}^{\infty} log (1-q^n) = -\sum\limits_{n=1}^{\infty}\sum\limits_{m=1}^{\infty} \frac{q^{n.m}}{m} ##, where ##q^{n}=e^{2\pi i n t} ## , ##t## [1] a complex number in the upper plane.Homework Equations Only that ## e^{x} =...
  21. jamalkoiyess

    Linear Algebra How Does Linear Algebra Help with Differential Equations?

    Hello PF, I have just finished my first semester in college and did Calc. 3. Now for the spring semester i have to take differential equations and i have been given the advice that linear algebra comes in handy when dealing with DEs. So can anyone recommend a good introduction for linear algebra...
  22. A

    Understanding the algebra behind these limit problems

    Homework Statement $$\lim_{x \to -∞}{\sqrt{x^2 + bx + c} - x}.$$Homework EquationsThe Attempt at a Solution So in problem 1, once I got to a point where I am to divide by the highest power in the denominator(x) I get something like: $$\lim_{x \to -∞}\frac{bx+c}{\sqrt{x^2+bx+c}+x}$$ Now what I...
  23. T

    Compare these two Linear Algebra courses

    Hi! First off, I am actually a math / econ major. I hope I'm still welcome here I am trying to figure out if it's worth it to take both of these courses or just one of them. I have not taken LA before. Course 1: Addition, subtraction and scalar multiplication of vectors, length of vector...
  24. S

    Algebra of displacement operator

    Homework Statement Given an operator ##D(\alpha)=\exp\ (\alpha a^{\dagger}-\alpha^{*}a)## and a function ##g(a,a^{\dagger})##, where ##a## and ##a^{\dagger}## are operators and ##\alpha## and ##\alpha^{*}## are complex numbers, show that ##D^{-1}(\alpha)g(a,a^{\dagger})D(\alpha)=g(a+\alpha...
  25. Cjosh

    Pulling fractional exponents out of an expression

    Homework Statement Find critical numbers of the function: F(x)=t^3/4 - 2t^1/4 Derivative I got: F'(x)=3/4 t^-1/4 - 1/2 t^-3/4 Homework EquationsThe Attempt at a Solution I have found the derivative and I understand I must pull out a t in order to find critical numbers, and run across this...
  26. Rococo

    Algebra simultaneous equations Question

    Homework Statement Let ##g_k = 2cos(k/2)## and ##z=e^{ip(N+1)}## where N is an integer. There are two simultaneous equations: ##E^2 = (g_k + e^{ip})(g_k + e^{-ip}) = 1 + g_k^2 + 2g_k cos(p) ## [1] ##(1+z^2)E^2 = (g_k + e^{-ip})^2 z^2 + (g_k + e^{ip})^2##[2]...
  27. caters

    Best Tunnel Shape for X,Y,Z Coordinates

    Homework Statement X,Y,Z(coordinates) What function corresponds to the best tunnel shape? g = 9.8 m/s^2(earth gravity) Homework Equations F(x)=Y G(x)=X^2 in the xy plane G(z)= sin(X) in the xz plane H(x)= parabolic sinusoid(X^2 and sin(X) both in the xy plane) The Attempt at a Solution I have...
  28. M

    MHB Finding B^-1 in 3x3 Matrices with Linear Algebra

    if A and B are 3x3 matrices such that: ABC = I, |3A|=81 and |C^T|= 2 , how to find |B^-1| I couldn't solve this because there is not much given.
  29. binbagsss

    I Solving SR Invariance: Minkowski Metric, Poincare Transformation, Index Notation

    I am following some lecture notes looking at the invariance of Poincare transformation acting on flat space-time with the minkowski metric: ##x'^{u} = \Lambda ^{u}## ##_{a} x^{a} + a^{u} ## [1], where ##a^{u}## is a constant vector and ##\Lambda^{uv}## is such that it leaves the minkowski...
  30. Rectifier

    Linear algebra - linear equation for a plane

    The problem I am trying to write the equation for the plane on the following form ## ax + by + cz + d = 0 ## $$ \begin{cases} x = 1 + s - t \\ y = 2 - s \\ z = -1 + 2s \end{cases} $$ The attempt ## s, t ## are the parameters for the two directional vectors which "support" the plane. $$...
  31. binbagsss

    I Index algebra questions / order of indices

    Hi, I've somehow gone the past year without paying attention to the order of the indicies when one is upper and one is lower i.e. that in general ##g^{\mu}## ##_{\nu}## ##\neq g_{\nu}## ## ^{\mu}##. A have a couple of questions : 1) ##g^{u}## ##_{v} x^{v}=x^{u}## [1] ##g _{v} ## ##^{u} x^{v}...
  32. M

    What algebraic property can I use here?

    Homework Statement [/B] example problem: 5 = [(x)(4+x)] / (4-x) answer: 5 Homework Equations Unsure what to use. 3. The Attempt at a Solution Not sure what my professor did, but I thought that if i multiply by the reciprocal of something, I have to balance by multiplying the other side as...
  33. S

    A Algebra - Clifford, Dirac, Lorentz

    In the representation theory of Lorentz transformations, the words Clifford algebra and Dirac algebra are used interchangeably. However, there is a distinction between the two. Indeed, the Dirac algebra is the particular Clifford algebra ##Cl_{4}({\bf{C}})\equiv Cl_{1,3}({\bf{C}})## with a basis...
  34. S

    A How Do Ladder Operators Annihilate States in SU(2) Algebra?

    Let the generators of the SU(2) algebra be ##\tau_{1}##, ##\tau_{2}## and ##\tau_{3}##. Consider an ##N## dimensional representation, which means that the ##\tau_{i}## are ##N \times N## matrices which act on some ##N##-dimensional vector space. Consider the ladder operators...
  35. caffeinemachine

    MHB Algebraic Closure of Fp [Lang, Algebra, Chapter 6, Problem 22]

    Problem. Let $K$ be the field obtained from $\mathbf F_p$ by adjoining all primitive $\ell$-th roots of unity for primes $\ell\neq p$. Then $K$ is algebraically closed. It suffices to show that the polynomial $x^{p^n}-x$ splits in $K$ for all $n$. In order to show this, it in turn suffices to...
  36. B

    A Notation/Site for Representations of an Algebra

    I'm currently reading the paper "Higher Spin extension of cosmological spacetimes in 3d: asymptotically flat behaviour with chemical potentials in thermodynamics" I'm looking at equation (3) on page 4. I know that symmetrization brackets work like this A_(a b) = (A_ab + A_ba)/2. However I have...
  37. B

    A 3dim Poincare Algebra - isl(2,R)

    The Poincare algebra is given by isl(2, R) ~ sl(2,R) + R^3. What exactly does the i stand for? Thanks a lot in advance!
  38. KDS4

    Rearranging variables Van Der Waals EoS into new variables

    The question I'm stuck on is: P = NKBT/(V-Nb) - aN2/(V2) -----> (1) Re-arrange variables in the Van Der Waals equation of state, Eq. (1), so that V always appears in the equation as V/(3Nb) and P appears as 27b2P/a. Then T should appear in the combination 27b kBT/(8a). Call these...
  39. Rectifier

    Boolean algebra - is it possible to simplify this expression to 0

    The problem I have been trying to solve a long problem but my answer differs from my books answer with just a few peculiar terms. My answer: ##x_1' \vee x_0'x_1x_2 \vee x_0x_1'x_2' \vee x_2## Book: ##x_1' \vee x_2 ## My question is: Is it possible to simplify ##x_0'x_1x_2 \vee...
  40. PhotonSSBM

    Boolean Algebra Proof (Distribution and XOR)

    Homework Statement Use the definition of exclusive or (XOR), the facts that XOR commutes and associates (if you need this) and all the non-XOR axioms and theorems you know from Boolean algebra to prove this distributive rule: A*(B (XOR) C) = (A*B) (XOR) (A*C) Homework Equations All the...
  41. Rectifier

    The Boolean Algebra XOR Problem: Are These Expressions Equivalent?

    The problem This is not a complete homework problem. I am at the last step of the solution to a long problem and only interested to know whether these following expressions are equivalent. My answer: ## a \oplus ab \oplus ac ## Answer in my book: ## a \oplus b \oplus c ## The attempt I...
  42. kyphysics

    Linear Algebra Any Great Linear Algebra Books for First-Time Learners?

    What are the best ones and why for a first-timer like myself (doing self-study)? Thanks very much everyone.
  43. NihalRi

    Electric force, theory and algebra.

    Homework Statement This question has two parts. There is a quarter or radius R that is charged with a net force of Q. A point like charge of net charge q,is at a distance z from the center of the quarter. Q1: Under what condition could we use Coulomb's law to find the magnitude the force...
  44. Rectifier

    Boolean algebra - distribution

    The problem I am trying to show that ##a'c' \vee c'd \vee ab'd ## is equivalent to ## (a \vee c')(b' \vee c')(a' \vee d) ## The attempt ## (a \vee c')(b' \vee c')(a' \vee d) \\ (c' \vee (ab'))(a' \vee d)## The following step is the step I am unsure about. I am distributing the left...
  45. MidgetDwarf

    Algebra Best Version of Euler: Elements of Algebra

    So I want to read Euler's : Elements of Algebra. However, I see many editions on Amazon. What is the best version of this book?
  46. R

    Quick question on intro to linear algebra book

    I'm looking at purchasing Algebra (2nd Edition) by Michael Artin, is this a good book to purchase as my first intro to linear algebra book for self learning?
  47. almarpa

    Algebra Similar book to Kleppner's Quick Caculus for linear algebra

    So anyone of you know a book that provides a gentle and quick refresher for linear algera, in the spirit of the book "Quick Calculus" by Kleppner and Ramsey? Now that I am studying quantum mechanics, I feel I need to review the linear algebra I studied during my engineering degree. Thanks.
  48. J

    MHB Algebra.... Answer should be 0?

    0.0162 * 0.000000000000002 divided by 0.000054 * 0.02 I keep getting 0 but when I try to see if its correct, it tells me its not. What the heck is the answer?
  49. J

    MHB Two elementary algebra problems

    #1. How many classrooms would be necessary to hold 1,000,000 inflated balloons? (Assume one balloon is about 1 ft3 and a typical classroom is about 30 ft × 45 ft × 15 ft. Round your answer to the nearest number of classrooms.) #2. Approximately how high would a stack of 1 million \$1 bills be...
  50. binbagsss

    QM Bra & Ket Linear Algebra Hermitian operator proof -- quick question

    Homework Statement Hi, Just watching Susskind's quantum mechanics lecture notes, I have a couple of questions from his third lecture: Homework Equations [/B] 1) At 25:20 he says that ## <A|\hat{H}|A>=<A|\hat{H}|A>^*## [1] ##<=>## ##<B|\hat{H}|A>=<A|\hat{H}|B>^*=## [2] where ##A## and ##B##...
Back
Top