Quadratic Definition and 989 Threads

  1. K

    Square roots in quadratic trinomial inequalities

    How do we treat expressions under a sqaure root in inequalities ? Like for ex. x+4< Math.sqrt(-x^2-8x-12) (sorry, using m.physicsforums, so i don't know what to use for a root, so JAVA :p) I request the use of this very example.
  2. K

    Ranges of simple quadratic functions

    Taking a general function with two quadratic eqs, Y = (ax^2+bx+c / px^2+qx+r) ax+bx+c = pyx^2+qxy+ry x^2(a-py) + x(b-qy)+(c-ry)=0 The discriminant turns out to be a+ve or a 0. So, (b-qy)^2 - 4(a-py)(c-ry) >or= 0 Now how does this equation yield a range for y?or can it?what are the next steps?
  3. K

    Graphing a standard quadratic equation?

    How do we graph a quadratic equation in the form ax^2+bx+c =0?, or an equation like , f(x)(or y)= [(x+b/2a)^2 - (D/4a^2)], where D = b^2 - 4ac? or how do we get a parabolic curve intersecting at its roots(of the quadratic equation) in the x axis?
  4. K

    Is expansion necessary for this quadratic equation?

    (x+3)(x-4)(x-2)(x+1) = 24 Can we change it into a quadratic equation without multiplying the expressions under those brackets?
  5. V

    Theory of quadratic equations

    theory of quadratic equations... theres a quadratic equation lx^2 + nx + n where its roots are in the ratio p:q .we need to prove that √(p/q) + √(q/p) + √(n/l) = 0 what i did was..i introduced a proportionality constant k... so pk + qk = -(n/l) while pq(k^2) = n/l...
  6. C

    Need to find c in a quadratic equation

    Homework Statement If α and \frac{1}{αα}are the roots of the equation 5x^{2}+13x+k then k will be: a) 5 b) -5 c) 13 d) 1 Homework Equations The Attempt at a Solution I've tried multiplying both the roots to get \frac{c}{a} and adding the roots to get...
  7. J

    MHB Arent quadratic functions supposed to be symmetrical?

    As we were talking about earlier. f(x) = x^2 + 3x + 6 f ' (x) = 2x + 3 P1 = (0, f(0)) f ' (0) = 3. This is not symetrical... I hope you guys enjoy my question bombarding. As there are a lot of maths concepts that make me want to cry. It's funny, half the people in my degree fail their...
  8. O

    How Do I Find the Energy of a Non-Hermitian Hamiltonian with Bosonic Operators?

    Hi all, There is a Hamiltonian in terms of "a" and "a^{dagger}"bosonic operators H=ω*(a^{dagger}a+1/2)+alpha*a^2+β*a^{dagger}^2 and ω, alpha and β are real constants and its energy is E=(n+1/2)*epsilon where epsilon is ω^2-4*alpha*β. Now, I tried to find this energy but I couldn't. Would you...
  9. karush

    MHB -4.3.1 find quadratic eq given 3 pts

    how do you find the quadratic equation given (-3,0) (3,0) and (0,-4) thus y=k(x-3)(x+3) for the zero's but how do you find k or any other better method of finding the equation thanks much(Cool)
  10. J

    General form of the quadratic equation

    I am trying to figure out how the coeffecients in the general second degree equation transform the function as they change through a range of values. I think that d and e are the proportion of x and y are horizontal and vertical shifts, but less sure about a, b, and c. Here is the equation as...
  11. B

    What are some interesting ways of proving the quadratic formula?

    Without the classic method of "completing the square" and factorising?
  12. P

    Relation between coefficients and zeros of a quadratic polynomial

    Homework Statement For any quadratic polynomial ax2+bx+c having zeros β and α Prove that β + α = -b/a and αβ = c/a. Homework Equations The Attempt at a Solution I have found a method myself to prove α+ β = -b/a. However, I could not prove αβ = c/a. It goes like this. If α and β are the...
  13. D

    Biomechanics Quadratic Equation problem

    Homework Statement 1. Neglecting the height of release, a ball is thrown vertically upwards at 20 m/s, find: d) time (s) that the projectile is at height 10.5 m. V1 = 20m/s a = -9.81m/s^2 d = 10.5m Homework Equations d = v1*t + 1/2 a(t^2) The Attempt at a Solution...
  14. Saitama

    Quadratic Equation: Finding Values of 'a' Between 2 and 4 with Only One Root

    Homework Statement Find all the values of 'a', so that exactly one root of the equation x2-2ax+a2-1=0, lies between the numbers 2 and 4, and no root is either equal to 2 or equal to 4.Homework Equations The Attempt at a Solution Let f(x)=x2-2ax+a2-1 I tried to visualize the question by graph...
  15. S

    Solution related to certain condition in quadratic equation

    Homework Statement For a constant k, consider the function f(x) = x2 + kx + k2 - 2k - 4 Find the range of k for which f(x) = 0 has one solution between 0 and 1 and the other solution between 1 and 2Homework Equations quadratic formula discriminantThe Attempt at a Solution x2 + kx + k2 - 2k - 4...
  16. N

    Is f(x,y) = a + bx + cy + dxy a Quadratic Polynomial?

    Hello, I just want to clear up a confusion. Is f(x,y) = a + bx + cy + dxy a quadratic polynomial? where x and y are variables and a,b,c,d are constants.
  17. R

    Solve Quadratic Equations for x: Mechanics Notes & Error Check

    Hey, I was going through some mechanics notes and came across this quadratic equation to solve for x. In my notes it is supposed to equal 3 however I do not get that result. I am not sure if I am simplifying it wrong or what. I am ending up with 2.12 for the positive value. Please let me...
  18. J

    MHB How Does Trigonometry Affect the Roots of a Quadratic Equation?

    http://www.screencatch.com/screenshots/13354664404923.jpg
  19. C

    Finding the solutions to a quadratic equation with a complex conjugate

    Homework Statement Find all solutions to z^2 + 4conjugate[z] + 4 = 0 where z is a complex number. Homework Equations Alternate form: 4conjugate[z] + z^2 = -4 The Attempt at a Solution I have tried solving this solution using the quadratic formula. However, √b^2 - 4ac = √16 - 4x1x4 = 0...
  20. X

    How to determine significant figures for quadratic?

    Homework Statement A student is running at her top speed of 5.0 m/s to catch a bus, which is stopped at the bus stop. When the student is still 40.0 m from the bus, it starts to pull away, moving with a constant acceleration of 0.170 m/s2. For how much time and what distance does the...
  21. azizlwl

    Solve Quadratic Equation: √(5x-1) - √x=1

    solve √(5x-1) - √x=1 eq. 1 transpose one of the radicals: √(5x-1)=√x+1 Square: 5x-1=x+2√x+1 Collect terms: 4x-2=2√x or 2x-1=√x Square: 4x^2-4x+1=x, x=1/4 , 1. x=1/4 is not the root by substitution to equation 1. ... My question what makes x =1/4 is not the root, only x=1 is the root.
  22. R

    Quadratic Formula (Equilibrium Points)

    Homework Statement The following is part of a solution to a problem about finding equiblirum points of a differential equation and sketching its bifurcation diagram http://img32.imageshack.us/img32/9194/63226925.jpg How did they get y= -1 \pm \sqrt{1- \mu}? Homework Equations The...
  23. J

    MHB Roots of $f(x)$ Quadratic Equation: $1x^2+2x+3=0$

    if $f(x)$ be a continuous and assumes only rational values so that $ f(2010) =1. $ then roots of the equation $f(1)x^2 + 2f(2)x + 3f(3) =0$ are
  24. S

    Finding vertex of quadratic equation?

    I have to find the vertex, axis, domain, & range of this quadratic equation: f(x)= -1/2(x+1)^2 -3 I can't remember how to do the vertex. Is it y= -b/2a? Also, I tried factoring the equation, but I think I messed up. I ended up with: f(x)= .25x^2 +.5x-2.75 Thanks
  25. E

    Maths - a proof question on the nature of roots of quadratic equations

    I'm sorry, I just realized I put this in the wrong subsection. While I figure out how to fix that, please have a look anyway. __ Homework Statement Given x \inℝ And s =\frac{4(x^{2}) + 3}{2x-1} Prove that s^{2} -4s - 12 ≥ 0 Homework Equations The discriminant Δ, (in order for which to be...
  26. T

    Understanding the Properties of Imaginary Cube Roots of Unity

    Homework Statement Let the roots of x2 + x + 1 = 0 be \alpha and \beta, form a quadratic equation with roots: (i) \alpha2, \beta2; and (ii) \frac{1}{\alpha}, \frac{1}{\beta}.The attempt at a solution sum of roots = \alpha + \beta = -1 product of roots = \alpha\beta = 1 (i) sum of roots =...
  27. B

    Product of quadratic nonresidues is a residue

    Homework Statement Prove that if p is prime, then if A is a quadratic nonresidue mod p and B is also a quadratic nonresidue mod p, then AB is a quadratic residue mod p. Homework Equations A is a nonresidue means A = x^2 (mod p) has no solutions The Attempt at a Solution I already...
  28. N

    Quadratic Potential: What Does It Mean?

    Hi group, I'm currently trying to understand a physicists written paper on ecological models. In there, they used the term "quadratic potential" when comparing spatial diffusion with a spring system (see attachment 1). After searching online for this term, I found nothing directly relevant to...
  29. L

    Comp Sci Solving Quadratic Equations: Invalid Inputs

    Homework Statement IMPLICIT NONE REAL :: A, B, C, DISCR, X1, X2, x1i, x2i CHARACTER(3)::ANS,ANS1 ! Reads the coefficients for the quadratic equation 33 WRITE(*,*)")"Please enter a *REAL*NUMBER* coefficient ( A )." READ(*,*)A WRITE(*,*)"Please...
  30. S

    How to Easily Factor a Quadratic Expression?

    2x^2+9x-5 here is the quadratic expression that I am trying to factor. Is there a way to factor this easily? I am getting confused on the signs. the book says the factor are: (2x-1)(x+5) but (-1)(2)+5=3 but why not (2x+5)(x-1)? and 5(2)=10-1=9 which looks like the correct answer...
  31. S

    What is the Smallest Surface Area of a Crate Delivered by Canada Post?

    Homework Statement Canada Post will deliver parcels only if they are less than a certain maximum size: the combined length and girth cannot exceed 297 cm (Girth is the total distance around the cross-section of the parcel). Canada Post delivers a crate with the smallest SA to your house. What...
  32. J

    Is a Quadratic Nonresidue of Odd Primes p and q Also a Nonresidue Modulo pq?

    If a is a quadratic nonresidue of the odd primes p and q, then is the congruence x^2 \equiv a (\text{mod } pq) solvable? Obviously, we want to evaluate \left( \frac{a}{pq} \right) . I factored a into its prime factors and used the law of QR and Euler's Criterion to get rid of the legendre...
  33. G

    Help understanding quadratic gravity

    Hi all. I keep coming across the term "quadratic gravity" in various GR papers and don't entirely understand the concept as it doesn't seem to be explained anywhere. It seems to appear most frequently in the context of pp-waves. So I was hoping somebody could enlighten me as to what its all...
  34. Y

    A question about quadratic residues

    I need to prove that a be a odd integer that congruence X^2\equiva mod 2 is always solvable with exactly one incongruent solution modulo 2. this question is linked with (b) let a be an odd integer. Prove that the congruence X^2\equiva mod 4 is solvable iff a\equiv1 mod 4. in this case ,prove...
  35. Y

    Number theory - quadratic residues

    number theory -- quadratic residues Homework Statement find all incongruent solutions of each quadratic congruence below. X^2\equiv23 mod 77 Homework Equations X^2\equiv11 mod 39 The Attempt at a Solution it is suffices to X^2\equiv23 mod 7, andX^2\equiv23 mod 11, then how to do next?
  36. T

    Sum of Squares of Roots of quadratic equations.

    1. The problem: Find the value of \lambda for which the sum of squares of the roots of the equation: 2x^2 + (2\lambda +4)x^2-(1+ \lambda) = 0 has minimum value. 2. Homework Equations \alpha + \beta = -b/a \alpha\beta = c/a where a,b,c are coefficients of x^2 , x and constant...
  37. C

    Quadratic function word problem with given equation.

    Homework Statement The profit, P, of a video company, in thousands of dollars is given by P=-5x^2+550x-5000, where x is the amount spent on advertising in thousands of dollars. a) Determine the amount spent on advertising that will result in a profit of $0. Homework Equations...
  38. ElijahRockers

    Quadratic Forms & Lagrange Multipliers

    Homework Statement I'm having trouble grasping http://www.math.tamu.edu/~vargo/courses/251/HW6.pdf. Our teacher has decided to combine elements from Linear Algebra, and understanding Quadratic forms with our section on lagrange multipliers. I am barely able to follow his lectures. If I look...
  39. C

    Finding transformations and base function of quadratic equation.

    Homework Statement For each of the following, identify the base function and describe the transformation(s): f(x)=-4(3x)^2 + 5 Homework Equations f(x) = -4(3x)^2 + 5 The Attempt at a Solution Alright so my attempt at figuring out the requested answers are: Base function = x^2...
  40. S

    Proving Quadratic Inequality: (x-y)^2 ≥ 0

    Homework Statement By expanding (x-y)^2, prove that x^2 +y^2 ≥ 2xy for all real numbers x & y. Homework Equations The Attempt at a Solution expanding (x-y)^2 x^2 - 2xy + y^2= 0 Hence, x^2 + y^2 = 2xy But where does the ≥ come into it? and why? when you put values in...
  41. K

    How do I slove this quadratic equation?

    Homework Statement I'm studying for the GMAT and the study materials do not include how to solve this equation. I need to know how to solve it without a calculator. Homework Equations If 2^x - 2^x-2 = 3(2^13), what is the value of X? The Attempt at a Solution The answer key says...
  42. R

    Rotation of axes to Eliminate the xy-term in a quadratic equation

    Homework Statement Rotation of axes to Eliminate the xy-term in a quadratic equation 3x^2 - 10xy + 3y^2 + 16 √2x - 32 = 0 2. The attempt at a solution I do not know the method that should be taken to solve this sort of question. That is what I am looking for. If anyone can point me...
  43. H

    Solution to quadratic equation doesn't look right

    Homework Statement Homework Equations distance = rate * time The Attempt at a Solution So the speed of the ball I have as: [t = time] 5 + 32t Which I believe makes sense because the ball is initially traveling @ 5 ft/sec, and after 1 second, the ball is traveling 37...
  44. N

    What are the Solutions to a Complex Quadratic Equation?

    Homework Statement Hello! z^2 - (7+2i)z + (12+8i) = 0 The Attempt at a Solution I used the quadratic equation and got: z = (7+2i)/2 +- sqrt( -3/4 - i) r = 5/4, and the argument is Theta = arctan(-1/-3/4) = 0.927 925 - Pi (since x < 0 and y < 0, right?) Then, I know that z =...
  45. PrincePhoenix

    What is the range of a rational function?

    Homework Statement The following equation defines a rational function.Find its Range f(x) = x2/(x-1) The attempt at a solution Let y = x2/(x-1) =>y(x-1) = x2 =>xy-y = x2 =>x2-xy+y = 0 comparing with the general form of quadratic equation ax2+bx+c = 0, a=1, b=-y, c=y...
  46. L

    Is a Quadratic Equation with b=0 or c=0 Still a Quadratic?

    A quadratic equation has the form y = ax^2 + bx + c. However, if c = 0, then y = ax^2 + bx. Is it still called a quadratic equation? And if b = 0 so that y = ax^2, is it still given the title of quadratic equation? I would guess yes since it still has a power of 2 and is a parabola. Is...
  47. P

    Calculate Speed for Motorbike Crossing a 40m Wide River Using a 53 Degree Ramp

    Homework Statement Motorbike crossing a river using a ramp. River is 40m wide, the bank on the opposite side is 15m lower. The ramp angle is 53 degress. What is the speed needed at take off? Homework Equations I am using s = ut for the horizontal and s = ut x 1/2 at2 I think because the bank...
  48. D

    Solve Quadratic Trinomials w/Large Coeffs: Factoring Tips

    I'm told that factoring is an important skill in calculus so I am avoiding using the quadratic formula. But for quadratic equations with large coefficients to factor, is there a better/faster way rather than guessing and checking every single combination?
  49. M

    Least squares estimation with quadratic constraints (M*M = 0)

    Hello there, currently I am trying to solve a least squares problem of the following form: min_{M} ||Y - M*X||^2 where M is a 3x3 matrix and Y and X are 3xN matrices. However, the matrix M is of a special form. It is a rank 1 matrix which satisfies M*M = 0_{3x3} and the trace of M is zero...
  50. T

    Obtaing a desired quadratic equation

    Homework Statement Get an inverted quadratic equation (-x^2) with maximum y=100 and roots x=0 and x=1/120. Homework Equations The Attempt at a Solution I tried changing the several terms of the quadratic equation, used the quadratic formula setting c=100, and x=0 with the...
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