Quadratic Definition and 965 Threads

  1. A

    Solve Quadratic Equation: 5x^2 - 16tx + 3t^2

    Homework Statement Solve 5x^2 - 16tx + 3t^2 for x without using quadratic formula. I am interested in understanding the technique - I have the answers already: t/5, 3t Homework Equations I have solved the subsequent question which is: tx^2 + (tT - 1)x - T = 0, which seems easier because...
  2. Saitama

    MHB Uncovering the Hidden Identity in Solving Quadratic Equation Challenge

    If the quadratic equation $x^2+(2 – \tan \theta)x – (1 + \tan \theta) = 0$ has two integral roots, then sum of all possible values of $\theta$ in the interval $(0, 2\pi)$ is $k\pi$. Find $k$.
  3. matqkks

    MHB Applications of quadratic residues

    I have covered the proofs of the laws of quadratic reciprocity (the Legendre and Jacobi symbols). However this treatment of quadratic residues has been pretty dry. Are there any real life applications of the quadratic residues?
  4. Z

    How Do You Solve for Time in Projectile Motion Equations?

    15=35 sin Theta*t -4.9t^2 I have tried solving for t, I do not know how to... please help thank you
  5. anemone

    MHB Maximizing $a+b$ given Quadratic Constraint

    Find the maximum of $a+b$, given $a^2-1+b^2-3b=0$.
  6. M

    Quadratic equation word problem

    1. Problem Barkley runs a canoe-rental business on a small river in Pennsylvania. Currently, the business charges $12 per canoe and they average 36 rentals a day. A study shows that for every $.50 increase in rental price, the business can expect to lose two rentals per day. Find the price...
  7. U

    Quadratic Stark Effect - Perturbation Theory

    Homework Statement Homework Equations The Attempt at a Solution With a parity operator, Px = -x implies x has odd parity while Px = x implies x has even parity. Things that puzzle me 1. Why is ##[H_0,P] = 0## and ##H_1P = -PH_1##? Is it because ##H_1 \propto z## so ##Pz = -z##? Then...
  8. S

    MHB How to solve this dreadful quadratic with paper and pen?

    600*sqrt{1-a^2/400}=578-a^2/2 Shorter and elegant tricks would be welcome!
  9. matqkks

    MHB Proof of Quadratic Reciprocity: Undergrad Friendly

    Does anyone know of an elementary proof of the Law of Quadratic Reciprocity. I am looking for a proof that 1st or 2nd year undergraduate can understand. Searching for a proof which is digestible for a student who is doing a first course in number theory.
  10. X

    Deriving the quadratic formula.

    1.Homework Statement Derive the quadradic equation, ax^2 + bx + c = 0, using the fallowing method. 1. Divide by a, if a =/ 0. 2. Move the constant to the other side of the equation. 3. Square half the coeffecient of bx and add it to both sides, fixate the negative sign on -c/a. 4. factor the...
  11. G

    Convergence of 10^-2^n. Linear, quadratic, cubic, quartic, hectic

    Homework Statement Show that the sequence {(p_{n})}^{∞}_{n=0}=10^{-2^{n}} converges quadratically to 0. Homework Equations \stackrel{limit}{_{n→∞}}\frac{|p_{n+1}-p|}{|p_{n}-p|^{α}}=λ where α is order of convergence; α=1 implies linear convergence, α=2 implies quadratic convergence, and so...
  12. Albert1

    MHB Solving Quadratic Equations: Find k

    the solutions of : $x^2+kx+k=0 " are $ $sin \,\theta \,\,and \,\, cos\, \theta $ please find : $k=?$
  13. A

    Prove that a function is the quadratic form associated to

    Homework Statement Let G:R2\rightarrowR be a C2 function such that G(tx,ty)=t2G(x, y). Show that: 2G(x,y)=(x,y).HG(0,0).(x,y)t The Attempt at a Solution G is C2, so its Taylor expansion is: G(x,y) = G(0,0) + \nablaG(0,0).(x,y) + \frac{1}{2}(x,y).HG(c).(x,y)t, where c lies on...
  14. J

    MHB What is the classification of this degenerate quadratic surface?

    The question is to classify/describe the following degenerate quadratic surface: x2 - 2xy +2y2 - 2yz + z2 = 0
  15. Matejxx1

    Solving Quadratic Equation with Solutions x1 and x2: How to Calculate x1-3+x2-3?

    1.given the equation a(3x2+2x+1)=4x-6x2-4 with the solutions x1 and x2 a) let a=0 without solving the equation calculate x1-3+x2-3 the correct answer is supposed to be -7/2 Homework Equations x1+x2=-b/a x1*x2=c/a The Attempt at a Solution The first thing I was that I put in...
  16. O

    Confidence Interval for Coefficient of Quadratic Fit

    I have a bunch of noisy data points (x,y), and I want to model the data as y = ax2 + bx + c + noise where noise can probably be assumed to be Gaussian, or perhaps uniformly distributed. My data is firmly inside of an interval and I'm only interested in modeling correctly inside of this...
  17. C

    How to find quadratic function

    I'm looking for the function y=ax^2+c with the given points (-3,89) (2,39). Thanks
  18. N

    How Does Z Influence Hyperbolas in the XY Plane of Quadratic Surfaces?

    4x^2-y^2+2z^2+4=0 x^2-y^2/4+z^2/2+1=0 -x^2+y^2/4-z^2/2=1 In the xy trace -x^2+y^2/4=1+k^2/2 taking k=0 will yield the hyperbola but what affect will z have on the resulting surface as it tends to +- infinity It appears to me that as z to +- infinity the hyperbola in the xy plane becomes...
  19. N

    Drawing Quadratic Surfaces: Tips for Rendering Sheets by Hand

    z=y^2-x^2 Trying to render these sheets by hand is very difficult for me. I can conceptualize the sheet in general by observing that the trace in z=y^2-k^2 follows the trace of z=k^2-x^2 as z tends to negative infinity. The opposite is also true as z tends to infinity. This information...
  20. Saitama

    MHB What Are the Conditions for a Quadratic Equation to Not Meet the X-Axis?

    Problem: If the curve $y=ax^2+2bx+c$, ($a,b,c \,\in\,\mathbb{R},\,a,b,c \neq 0$) never meet the x-axis, then a,b,c can't be in A)Arithmetic Progression B)Geometric Progression C)Harmonic Progression D)All of these Attempt: Since, the curve never meets the x-axis, we have the condition...
  21. M

    Can we visualize the parts of a quadratic equation as area and length?

    consider the equation: ax^2+bx=c imagine that the constant c is divided into to parts: c=Z+Y where ax^2= Z and bx=Y so basically could we say c is part area and part length?? Sorry if the question is not explained better but that's the best way I came up with to describe it.
  22. matqkks

    MHB Introducing Quadratic Residues: Real World Examples & Law of Reciprocity

    What is the most motivating way to introduce quadratic residues? Are there any real life examples of quadratic residues? Why is the Law of Quadratic Reciprocity considered as one of the most important in number theory?
  23. PhizKid

    Completing the square using a matrix in quadratic form

    Homework Statement Complete the square using the symmetric matrix that defines the given quadratic form: ##x^2 - 4xy + 6xz + 2xt + 4y^2 + 2yz + 4yt + 5z^2 - 6zt - t^2## and write this quadratic as the sum and difference of squares after completing the square using the matrix. The Attempt at...
  24. K

    System of Equations Involving a Quadratic: Have Answer <> Understand

    Homework Statement Solve this system of equations for x and y. v=x+y v^2=x^2+y^2 Homework Equations The quadratic formula: x = (-b +/- sqrt(b^2-4*a*c))/(2*a) The Attempt at a Solution A TA gave the following advice: "Make y the subject of the first equation. Find y2 in terms of v and x...
  25. N

    How can you easily graph the trace of z=y²-x²?

    In equation z=y^2-x^2 when graphing the trace for y^2-x^2=k I see we have y=+-x for k=0 else y=+-sqrt(k+x^2) is there a simple way to graph this
  26. N

    Graphing Quadratic Surfaces: Tips for Substituting and Finding Traces

    Z=y^2-x^2 Is it always best to substitute k for each and plug in 0, +-1, +-2 to graph each trace.
  27. N

    What Are the Hyperbolic Characteristics of the Quadratic Surface Z=x²-y²?

    Z=x^2-y^2 The book is showing the trace for z=0 to be a hyperbola however I see y=x and y=-x
  28. Y

    What is the correct way to calculate the discriminant in a quadratic equation?

    I know for ##ax^2+bx+c=0##, x=\frac{-b^+_-\sqrt{b^2-4ac}}{2a} Using ##x^2-3x-4=0##, we know it is equal to ##(x+1)(x-4)=0##. So ##x=-1## or ##x=4##. but using the formula: x=\frac{-b^+_-\sqrt{b^2-4ac}}{2a}=\frac{3^+_-\sqrt{9+4}}{2}=\frac{3^+_-\sqrt{13}}{2} I cannot get -1 and 4...
  29. F

    MHB Classify Quadratic Surfaces: Ellipsoids, Hyperboloids, Paraboloids & Cylinders

    On the basis of the eigenvalues of A, classify the quadratic surfaces X'AX+BX+k=0 into ellipsoids, hyperboloids, paraboloids and cylindres. Can somebody help me to solve the problem?
  30. Sudharaka

    MHB Normal Form and Canonical Form of a Quadratic

    Hi everyone, :) Take a look at the following question. Problem: Determine which of the following quadratic functions \(q_1,\,q_2:\,V\rightarrow\Re\) is positive definite and find a basis of \(V\) where one of \(q_1,\,q_2\) has normal form and the other canonical...
  31. Sudharaka

    MHB Reducing Quadratic Form to Principle Axes

    Hi everyone, :) Here's a question with the summary of my method of how to solve it. I would really appreciate if you could go through it and let me know if there are any mistakes with my approach. Also are there any easier methods? Problem: Find an orthogonal transformation that reduces the...
  32. T

    MHB Solving a Quadratic Binom: Who's Right?

    It was given this term: $$\sqrt{1-(x^2+1)^2}$$ My friend got the solution $$-x^2$$,but i think he is not right a about that,cause i believe you should first solve the quadratic binom,which is $$x^4+2x+1$$,so my solution is: $$\sqrt{1-x^4-2x-1}$$ or $$\sqrt{-x^4-2x}$$ Im wondering who is right...
  33. S

    Understanding the Derivation of the Quadratic Formula

    This could be seen as a rather "basic" math question, but it is a topic of curiosity for me. I'm currently a senior in high school, taking a pre-ap pre-cal/trig/AP-Calculus double blocked class. I'm absolutely fascinated by mathematics, and something of keen interest to me is the derivation of...
  34. Q

    Extrema of Quadratic functions

    Homework Statement Does every quadratic function have a relative extrema? Homework Equations Quadratic function: ax^2 + bx + c. Aka a polynomial. Polynomials are continuous through all real numbers. The Attempt at a Solution It seems as if all quadratic functions would have...
  35. M

    Quadratic equation - how to understand the impact of the middle term?

    Hi, I am trying understand if there is a quick way to figure out the impact of the X term in a quadratic equation. For example, by looking at the following equation, I know that it is a parabola (X^2) ; by looking at 24, I know that it is the y-intercept. However, I don't know what is the...
  36. Saitama

    Quadratic equation and trigonometry

    Homework Statement If the quadratic equation ax2+bx+c=0 has equal roots where a, b and c denote the lengths of the sides opposite to vertices A, B and C of a triangle ABC respectively, then find the sum of integers in the range of $$\left(\frac{\sin A}{\sin C}+\frac{\sin C}{\sin...
  37. W

    What Determines the Minimum Value in a Quadratic Equation?

    Homework Statement 4. If x1, x2 are two real number roots of real number coefficient quadratic equation: $$x^2 -2mx + m + 2 =0$$ Solve the following questions: (1) What are the values of m so that x1=x2? (2) What are the...
  38. J

    MHB Algebra Problem About Quadratic Function

    These 3 equations all describe the same quadratic function. What are the coordinates of the following points on the graph of the function? From which equation is each point most easily determined? y = (x - 5) (x + 1) y = x ^ 2 - 4x - 5 y = (x - 2) ^ 2 - 9 X-intercept, what are the points...
  39. MarkFL

    MHB Supeerstar's questions at Yahoo Answers regarding optimizing quadratic functions

    Here are the questions: I have posted a link there to this topic so the OP can see my work.
  40. A

    Understanding Factoring a Quadratic Equation: Common Mistakes and Solutions

    Homework Statement Question + attempt: Homework Equations The Attempt at a Solution Why is it that when I expand the factored form, I don't get the original equation?
  41. B

    How to Solve a Quadratic Equation Using Factorisation?

    Solve the following quadratic equation. Use factorisation if possible. X2 - 4X - 8 = 0 Normally I wouldn't have trouble factorising a quadratic, but I have just been introduced to a new way to do it and I want to use this way to answer the question. Here's how far I get, then I'm unsure what...
  42. MarkFL

    MHB Help's question at Yahoo Answers regarding quadratic modeling

    Here is the question: I have posted a link there to this topic so the OP can see my work.
  43. MarkFL

    MHB Quadratic Equations: Cedric Cajigas' Qs Answered

    Here are the questions: I have posted a link there to this topic so the OP can see my work.
  44. F

    Quadratic Simultaneous Equation

    Homework Statement Solve the equation for x y^2 = 4x x^2 = 4y Homework Equations None The Attempt at a Solution y^2 -4x = x^2 - 4y = 0 I have spent ages re-arranging and substituting in values but I just cannot solve this thing.
  45. MarkFL

    MHB Difference Quotient for Linear and Quadratic Functions

    Here are the questions: I have posted a link there to this topic so the OP may see my work.
  46. M

    Quadratic inequalities for complex variables?

    Hello, I was looking at Riley's solution manual for this specific problem. Along the way, he ended up with a quadratic inequality: If you looked at the image, he said it is given that λ is real, but he asserted that λ has no real roots because of the inequality. Doesn't that mean λ is...
  47. caffeinemachine

    MHB A theorem on Quadratic Forms in Reid's Book not at all clear.

    Hello MHB, I have been reading a book on Algebraic Geometry by Reid. On page 15, there's a theorem on Quadratic forms. The book doesn't explicitly define what a Quadratic Form is. From Hoffman & Kunze's book on Linear Algebra I found that given an inner product space $V$ over a field $F$, the...
  48. N

    MHB Quadratic and logarithmic models (new post)

    Here is my previous post! please look at pages 3 - 4 to see what I am talking about. http://mathhelpboards.com/pre-algebra-algebra-2/mathematical-modeling-6006-4.html I figured out how to input the quadratic and logarithmic equations into wolfram, this is what i got. Let me know if its correct...
  49. MarkFL

    MHB Richard Perito: Find Quadratic with Roots -1 +/- i√2

    Here is the question: I have posted a link there to this topic so the OP can see my work.
  50. H

    How Does Quadratic Air Resistance Affect a Puck on an Incline?

    Homework Statement I kick a puck of mass m up an incline (angle of slope = θ) with intial speed v0. There is no friction between the puck and the incline, but there is air resistance with magnitude f(v) = cv2. Write down and solve Newton's second law for the puck's velocity as a function of...
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