Elimination Definition and 164 Threads

An elimination reaction is a type of organic reaction in which two substituents are removed from a molecule in either a one- or two-step mechanism. The one-step mechanism is known as the E2 reaction, and the two-step mechanism is known as the E1 reaction. The numbers refer not to the number of steps in the mechanism, but rather to the kinetics of the reaction: E2 is bimolecular (second-order) while E1 is unimolecular (first-order). In cases where the molecule is able to stabilize an anion but possesses a poor leaving group, a third type of reaction, E1CB, exists. Finally, the pyrolysis of xanthate and acetate esters proceed through an "internal" elimination mechanism, the Ei mechanism.

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  1. JasonHathaway

    Differential equations: Elimination of arbitrary constants

    Homework Statement Find the differential equation of ln y = ax^2 + bx + c by eliminating the arbitrary constants a, b and c. Homework Equations Wrosnkian determinant. The Attempt at a Solution I've solved a similar problem (y=ax^2+bx+c --> y'''=0), but couldn't do the same with...
  2. Portal.Leaf

    Elimination of Arbitrary Constants (Differential Equations)

    Homework Statement Eliminate the arbitrary constants of the equation: ax2 + bx + cHomework Equations (Concept) According to my instructor, having n arbitrary constants makes an nth-order differential equation.The Attempt at a Solution I tried to differentiate 'til I get a third derivative so I...
  3. U

    Solving Equations with Gaussian Elimination: Troubleshooting Mistakes

    Homework Statement When solving 2 equations using gaussian elimination, can we divide one equation by the other? Can you help me find where I went wrong? Homework Equations 4x + 2y = 14 2x-y=1 The Attempt at a Solution
  4. L

    Solving Digitoxin Rate of Elimination with Geometric Progression

    Homework Statement Patients with certain heart problems are often treated with digitoxin, a derivative of the digitalis plant. The rate at which a person's body eliminates digitoxin is proportional to the amount present. In 1 day, about 10% of any given amount of the drug will be eliminated...
  5. B

    MHB Eliminating constants in a second derivative of a function

    Eliminate the constants $y=c_1 e^{ax}cosbx +c_2e^{ax}sinbx$ since there's two constants I took the derivative twice $y'=c_1\left ( -e^{ax}b\sin{bx} + ae^{ax}\cos{bx}\right )+ c_2\left ( e^{ax}b\cos{bx} +ae^{ax}\sin{bx}\right )$ $y''=c_1\left [ \left (...
  6. 9

    2x + y = 8, x - z = 2. Solve by elimination and substitution

    Homework Statement 2x + y = 8, x - z = 2. Solve by elimination and substitutionHomework Equations 2x + y = 8, x - z = 2 The Attempt at a Solution It cannot be solved by elimination or substitution.
  7. B

    MHB Elimination of arbitrary constants 2

    eliminate the arbitrary constant, 1. $\displaystyle y=mx+\frac{h}{m}$ h is a parameter, m to be eliminated.2. $cxy+c^2x+4=0$ eliminate c I don't know where to start please help me get started. thanks!
  8. B

    MHB Elimination of arbitrary constants.

    1. eliminate B and $\alpha$ from the relation $\displaystyle x=B cos(\omega+\alpha)$ in which $\omega$ is a parameter(not to be eliminated). I first took the two derivatives of x with respect to t: $\displaystyle \frac{dx}{dt}=-\omega B\sin(\omega+\alpha)$ $\displaystyle...
  9. Q

    Use of guassian elimination to find the determinate of a matrix

    Homework Statement I have to find that the characteristic polynomial for a 3x3 matrix A, which is effectively the same as finding the det(A - I*lamda) matrix A is: the problem is that when I've written out 'A - I*lamda' in matrix form, the three values at the bottom left of the matrix...
  10. K

    MHB Exact inversion of matrix complexity (by Gaussian elimination)

    I would like to check if what I have done is correct. Please, any input is appreciated. **Problem statement:** Consider a non-singular matrix $A_{nxn}$. Construct an algorithm using Gaussian elimination to find $A^{-1}$. Provide the operation counts for this algorithm. **My attempted algorithm...
  11. T

    How can I improve my GE program using MATLAB?

    Homework Statement I am writing a GE program and i think i have that correct. I have a matrix and i am trying to find the correct answer. I am not sure where i am going wrong. Homework Equations The Attempt at a Solution %GE with no pivoting function x=ge_nopivot(A,b)...
  12. AJBMuir

    Matrix multiplication, specifically elimination matrices.

    I was wondering if anybody can see where I have gone wrong here? I was given the rule, E2(E1A1)=(E2E1)A1, I can't seem to find my mistake.
  13. M

    What is the next step after LU decomposition for solving Ax=b?

    I have Ax=b problem where A 1484x1484 matrix,b 1484x1. A is sparse(95% zeros) but if I go for LU decomposition what should be the next step? Or is there any other method,I forgot algebra,learned it when I was undergrad long time ago.
  14. D

    Help Setting up an Equation to use the Elimination Method

    Homework Statement The question is to solve the IVP: x'=2x+y-e^2t & y'=x+2y, where x(0)=1, y(0)=-1Homework Equations Arranging the equations and substituting in D for the derivatives, the equations become: 1. (D-2)x-Dy= -2e^2t 2. (D-2)y-Dx= 0 The Attempt at a Solution My first attempt was...
  15. B

    Gaussian elimination: Proof of correctness

    I have been looking for a proof of correctness of Gaussian elimination, but alas, without much success. Most online resources explain how to apply the algorithm rather than proving correctness. That said, I have been looking for a proof to the following theorem, which is stated in Friedberg's...
  16. jaumzaum

    Substitution vs Elimination on halides

    If you add a strong base to a halide, you get mostly the alkene. If you add a weak base, especialy on primary halides not branched on the β carbon, the product is mostly the substituted. Why is that? 1) The mechanism for the substitution reaction is the heterotytic break of the C-X (where X is...
  17. A

    Can Elimination Method Reduce the Order of Differential Equations?

    Dear Fellows, I want to solve 4 differential homogeneous equations for non trivial solution. I have found two methods 1) Determinent. 2) Elimination By det. I got 8th order resultant equation and by second method I got 10th order. As each of initial equation is 2nd order so 8th is correct. But...
  18. I

    Modifying a Gaussian Elimination Algorithm to Perform Gauss-Jordan E.

    Homework Statement I have an algorithm that implements Gaussian elimination. According to the text, with some modification of the indices and their in the loops, I should be able to have this algorithm perform Gauss-Jordan elimination. I also have to reduce the matrix to reduced row-echelon...
  19. P

    Eliminating Elements in Commercial FEA Solvers

    I want to why actually elements are eliminated in commercial fea solvers. There is a criterion like stress or strain at which elements having acheived that state are eliminated. Wouldnt it lead to wrong results because, the material at eliminated elements place has become null.
  20. Τ

    E2 elimination of (E) and (Z) Acids?

    Homework Statement Both (E)- and (Z)-2-chlorobutenedioic acids dehyrochlorinate to give acetylene dicarboxylic acid. This reaction proceeds through the addition of a base and an E2 elimination. The (Z) acid reacts about 50 times faster than the (E) acid. Explain why. 2. The attempt at a...
  21. I

    Solving Linear System of Equations: Elimination

    Homework Statement A general system of linear equations is ax+by=e cx+dy=f where a,b,c,d,e,f are constant values. a)Use elimination to solve for x and y in terms of a,b,c,d,e,f. b)Are there any values that a,b,c,d,e,f cannot have?The Attempt at a Solution For part A, I got x=(e-f)/(a-c)...
  22. C

    Solving a System by Gaussian Elimination: Help Needed

    Homework Statement for some reason I am having real trouble trying to solve this system. Homework Equations The Attempt at a Solution a=(10,11,4) v1=(2,1,4) v2=(-1,-2,1) v3=(3,3,-1) the qstn does a belong to the span (v1,v2,v3)? so I do gauss elim but I keep running...
  23. matqkks

    Real Life Applications of Infinite Solutions with Gaussian Elimination

    I would normally use Gaussian ELimination to solve a linear system. If we have more unknowns than equations we end up with an infinite number of solutions. Are there any real life applications of these infinite solutions? I can think of solving puzzles like Sudoku but are there others?
  24. J

    Finding a basis in ImT using Gaussian Elimination

    Homework Statement $$ \begin{pmatrix} -1&3&0\\ 2&0&-1\\ 0&-6&1 \end{pmatrix} $$ Finding the ImT basis of this The Attempt at a Solution I got it down to $$ \begin{pmatrix} 1&0&-1/2\\ 0&1&1/6\\ 0&0&1 \end{pmatrix} $$ I know that by the principle of having pivots as the only non-zero...
  25. R

    Applying Gaussian Elimination to a Matrix - Understanding the Correct Method

    Homework Statement Apply Gaussian elimination to the following matrix 2 -3 0 3 4 -5 1 7 2 -1 -3 5 I understand how to get the answer. The Attempt at a Solution My question is why doesn't the following method work: Switch Z over into the first column, move row 1 to row 3, then exchange rows...
  26. Z

    Gaussian Elimination rules - apply to rows only?

    Homework Statement In this video; the uploader states at 0:47 that there are three rules. 1. Can swap rows 2. Can multiply a row by a constant 3. Can add a multiple of one row to another Do these rules apply only to rows? Can they be applied to columns? The uploader has not stated...
  27. M

    Comp Sci Using fortran to Solve linear equations using gauss elimination and back substitution

    Homework Statement What will be the value of the variable ipvt and AMD when the input value of lud to the following subroutine (solver) is zero ? subroutine Solver (A,B,N,lud,Z) integer lda,N,ipvt(1000),info,lud,IDAMAX &j,k,kp1,l,nm1,kb double precision...
  28. S

    Understanding Gaussian Elimination Matrices for Solving Linear Equations

    Homework Statement What is the Gaussian elimination matrix for the vector for the vector v=(2,-10,16,2)? The Attempt at a Solution I don't understand the question. What is a "Gaussian elimination matrix for a vector?" I know that Gaussian elimination is a method for solving a system of...
  29. R

    Matrix prerequisities for Gauss elimination

    hi all, Is there any matrix pre-requisities for Gauss elimination. Working on linear equations, I think I 've composed the global(stiffness) matrix of the LHS of linear equation.And found on the net the working code which uses Gauss elimination method, in the code beginning it checks...
  30. C

    Medical Do Diuretics Affect Drug Elimination Rates in Urine Tests?

    Do diuretics increase the elimination rates of drugs by increasing the volume of urine excretion?
  31. P

    Gauss elimination vs Solution with Inverse

    Homework Statement Using Octave or Matlab solve random binary matrices(with 1s and 0s) of size N and plot them together. Draw a conclusion. The Attempt at a Solution http://img703.imageshack.us/img703/7803/plotm.png I was just wondering if this looks correct to you. I previously had...
  32. T

    Gauss elimination algorithm for matrix inversion

    Hello guys, I'm writing a C++ function for matrix inversion. I saw many algorithms online, but I'm concerned about the case when a diagonal element equals zero, which is, for some reason, not taken into account by those websites. When we do the elimination for solving a system of linear...
  33. M

    Solving via Gaussian Elimination

    Homework Statement Solve the following system of equations using Gaussian Elimination: -2a+5c=1 a+2b-c=2 3a-2b=3 Homework Equations N/A The Attempt at a Solution Augmented matrix (-2 0 5 | 1) R2 → R2 +R1/2 (1 2 -1 | 2) R3 → R3 - 3R2 (3 -2 0 | 3) (-2 0 5 | 1) Swap R2 and...
  34. N

    Gaussian Elimination, is this method OK?

    Homework Statement A= <1, -3, -1, 1> <2, -5, 0, 1> <-3, 5, -6, 3> What I did was Row2 = 2*Row1 - Row2 which renders Row2 as: <0, -1, -2, 1> However in the solutions, Row2 was given as: <0, 1, 2, -1>, which appears to be R2 = -2R1 + R2 I'm guessing it makes no real difference...
  35. X

    Online tools for Gaussian elimination / LU decomposition ?

    I can not find any useful online tool that solves you a system of equations using Gaussian elimination and LU decomposition. So just a system like: -3X+4X+9X+4x=-2 9X+2X+1X-5X=2 etc. Just about 4 lines. several lines. So basically an online tool where you can just plug in the...
  36. G

    Gaussian Elimination Solve for variable

    Homework Statement Determine the value of k for which the system x + y + 2z = 3 x + 2y -4z = -3 2 + 8 + kz = -29 has no solutions. Homework Equations None The Attempt at a Solution Converting to a matrix 1 1 2 3 1 2 -4 -3 2 8 k -29 r2=r2-r1 1 1 2 3 0 1 -6 0 2 8 k -29...
  37. Z

    Systems of linear differential equations by elimination?

    The original form: http://img190.imageshack.us/i/79624585.png/ http://img685.imageshack.us/i/70092098.png/ I have manged to get to (D + 1)x + (D2 +D +1)z = 0 but after that I am kind of lost.
  38. A

    Gauss-Jordan Elimination Rules

    Can someone please explain the basic rules that must be adhered to when using Gauss-Jordan Elimination? I've been having some difficulty with it because apparently I keep doing things that you aren't allowed to do. So far, I know only the following: -You CAN multiply an entire row by a...
  39. A

    Oh god Gauss-Jordan Elimination.

    1. Homework Statement : 2. Relevant equations: Not applicable. 3. The attempt at a solution: This is where the problem begins. It's funny, because I used to be good at matrices back in high school, but when I look at them now, I don't understand why I keep getting different answers when I...
  40. X

    What is exactly pivoting ( in Gaussian elimination)?

    In terms of programming. Like, let's say you have F1+F2+F3+15=0 and you move the 15 to the other side, just as you're supposed to, which would be F1+F2+F3= -15. Is that what they mean by pivoting? The code moves the 15? thanks
  41. K

    How Does Gaussian Elimination Help Solve Systems of Equations?

    Homework Statement Using Gaussian Elimination: 3x - 2 y = 5 6x-4y =7The Attempt at a Solution [ 3 -2 5] [6 -4 7] * top row by 1/3 [1 -2/3 5/3] * Top row by -6, add to bottom row: [0 0 -3] So I get this: [1 -2/3 5/3] [0 0 -3] How can 0y equal -3?
  42. X

    How to Adapt This Gaussian Elimination Code for a 17x17 Matrix?

    I have this code for a Gaussian Elimination: As you can see, the input is A and b. I'm trying to figure out how I can make this code work for this Gaussian Elimination: http://img189.imageshack.us/f/50468910.png/ It's 17 rows. The code can do 17 rows. But some of the equations aren't in the...
  43. X

    Solving Gaussian Elimination Homework

    Homework Statement http://img189.imageshack.us/i/50468910.png/ Homework Equations The Attempt at a Solution I'm wondering how I do this? I don't really know. Supposed to be 17 rows. How many columns and how many each row? No clue! And how do I get the numbers for the matrix here?
  44. D

    Elimination Reaction: OH & H Removal Explained

    For the elimination reaction of ethanol: How come only the OH and H get taken out? I understand that you have to take out one atom from each carbon, so how come we can't take out, for example, one H from the left carbon and one H from the right carbon to get? Or is it mandatory to take...
  45. M

    2x2 matrix elimination / substitution

    Homework Statement I'm following an online course on linear algebra where matrix elimination was explained. They showed this for a 3x3 matrix, I wanted to test this with a 2x2 matrix but somehow managed to do something wrong.. I have two equations with 2 unknowns: 2x - y = 0 -x + 2y = 3...
  46. H

    Gaussian Elimination Solution to the 2D Poisson Equation

    I am trying to use Gaussian elimination to solve the 2D poisson equation. I've done this for the 1D problem without problems, but for some reason my solution for the 2D problem is incorrect; it looks something like the correct solution but it's as if the resulting field were cut in half, so...
  47. P

    Finding Perpendicular Vectors in R^4 Using Gaussian Elimination

    Find all vectors in R^4 that are perpendicular to the three coloumn vectors [1 1 1 1], [1 2 3 4], [1 9 9 7] sorry i don't know how to make them verticle guassian elimination or Ax=b I know that the dot product must equal 0 but I am not sure how to solve it
  48. C

    Solving for v0: Elimination Method Homework

    Homework Statement Homework Equations how do u solve for v0 from these two equations 1.)A0*v0=Av and 2.)v^2=v0^2+2gh... The Attempt at a Solution the sol is v0=[2gh*A^2/(A0^2-A^2)]^1/2... but i don´t know to get it... please help
  49. C

    Understanding Syn and Anti Elimination in E2 and Sn2 Reactions

    Can someone please help me understand the difference between syn and anti elimination in terms of what they favor? My [extremely] limited understanding leads me to believe that syn elimination favors E2 since it mimics frontside attack, which will not work for Sn2 since there is no net-bonding...
  50. M

    Power System Analysis: Node Elimination Explained

    Preface: I am an electrical engineer studying for the PE exam. I am reviewing power system analysis and have come across something I do not remember in any of my classes. I'll not bore you with the entire problem. Suffice it to say there is a 4x4 matrix that is being partitioned as follows...
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