1. H

    Difference equation with Z-Transform

    An investor opens an account at a investment firm earning 6% interest (annual rate) with an initial deposit of $6000. Each month , the investor makes a deposit of $150, but the bank charges a $10 fee. Write a difference equation describing the balance at month (n+1) given the balance at month n.
  2. X

    Unit tangent vector vs principal normal vector difference

    http://mathwiki.ucdavis.edu/Core/Ca.../The_Unit_Tangent_and_the_Unit_Normal_Vectors In the link, I cant understand that why the Principal Unit Normal Vector is defined by N(t) = T'(t) / | T'(t) | ,can someone explain.... Since tangent vector is normal to principal normal vector, why the N(t)...
  3. B

    Sum and difference identities help?

    The following relationship is known to be true for two angles A and B: cos(A)cos(B)-sin(A)sin(B)=0.957269 Express A in terms of the angle B. Work in degrees and report numeric values accurate to 2 decimal places. Enter your answer as an expression. Be sure your variables match those in the...
  4. J

    The difference quotient and the simplified answer containing radicals.

    I am working on trying to figure out why the worked out example of this difference quotient give a simplified answer with radicals in the denominator. I have been told by more than one person in the past that having radicals in the denominator is bad practice and should be avoided. Also, there...
  5. M

    Difference between a percentage increase happening each year between two dates and

    I am trying to explain why there is a difference between a percentage increase happening each year between two dates and then when comparing the overall increase. For example 1980 - £25,000 sales; 1981 - £26,000 sales; = 4% increase 1982 - £27,000 sales. = 3.85% increase When adding up the...
  6. T

    Not understanding the physics difference between first moment and second moment.

    I know the second moment is known as the moment of inertia, and the first moment is used to find the centroid, but I'm not quite sure if I understand the conceptual understanding of the moments themselves. Here is what I think: The first moment respect so some axis is the average weighted...
  7. I

    Difference Equation

    The equation is (x+y+z)dy/dx = 1. How will I solve it? Firstly, I arranged them by putting x and y on separate side. Then integrated it. But the answer is not matching.
  8. I

    Difference Equation

    Hi, I just came across a question which says that " If alpha and beta are the roots of the equation X squared - 2X + 4, Find alpha to the power n + beta to the power n. How will I solve this?
  9. M

    Evaluate the difference quotient for each function f(x)

    Hi so I need help on this problem: f(x)=4x^2-6 I know the formula is f(x+h)-f(x) over h I just keep trying it and I keep getting the wrong answer. THE ANSWER IS : 8x+4h I did: 4(x+h)^2-6 -(4x^2-6) <-- So I basically just plugged in the formula all over h, then I got 4x^2+2xh+h^2 -6...
  10. sakonpure6

    How do you tell the difference between a vector field and a vector function?

    Hello, I am studying vector calculus and am currently dealing with Green's theorem and line integrals. What I don't get is how do you differentiate between a vector function and a vector field? They both look the same to me. Moreover, does Green's Theorem only apply to questions using vector...
  11. Vinod

    Proving the relations between mean operator and central difference operator and hD

    Hi members, I am trying to prove the following relation but still unable to prove. $\frac{U}{\delta\mu}=\frac{U}{\delta}\left(1+\frac{\delta^2}{4}\right)^{\frac{-1}{2}}=1-\frac{\delta^2}{6}+\frac{\delta^4}{30}-\frac{\delta^6}{140}+0(\delta^8)$ I know $\frac{U}{\delta\mu}=\frac{U}{sinh U}$ and...
  12. B

    Percent change vs percent difference

    I'm having trouble wrapping my mind around this simple concept. I could really use an outside perspective. Here is the situation : Any dose given to a patient must be within 10% of the prescribed dose. If the prescribed dose is 2.14 mg and the dose given was 2.29 mg what formula should I be...
  13. B

    Having issues with expressing a trig problem as a sum or difference.

    I recently came across this question: cosAcos4A I have never dealt with anything higher than cos2A, but I'm guessing you have to split the cos4A into cos(2A+2A), and solve that way. Is there a way to express this as a single cos value? It seems like this takes a million steps to simplify. So...
  14. D

    summation of difference

    Can anyone explain why the formula of any term is f(r) -f(r-1) ???
  15. J

    Find the Difference between Positive and Negative Numbers.Result Needs to be Positive

    I'm trying to find an equation to find the difference between two numbers, and have the result be positive regardless of whether the result is negative or positive. For example, if X = 600 and Y = 300 then the difference would be 300 using X - Y, however if X = -600 and Y = -300 then the...
  16. sakonpure6

    The Difference between a Gradient and the good ol' derivatives?

    What is the difference between a Gradient and the good ol' derivatives? and how does a gradient help us get the derivative in any direction? Edit: I did some reading here http://betterexplained.com/articles/vector-calculus-understanding-the-gradient/ and the author says: Why is that true...
  17. lastxcloud

    Finite difference method nonlinear PDE Problem

    i want to solve a nonlinear PDE with finite difference method , from my academic background , i know how to use finite difference method to solve linear PDE , what's the right way to use FDM to solve nonlinear PDE or could someone provide me with book's titles or articles that can help me...
  18. Z

    Difference equation gone wrong

    The picture says it all, sorry for the scribbles
  19. T

    Difference of proportion hypothesis test

    If I am given two samples of the rate of production of 2 factory conveyor belts, and I am asked to perform a hypothesis test on whether one produces more per hour by 5%. How do I calculate the percentage difference. Is it as simple as setting the null and alternative hypothesis to be equal to...
  20. A

    Logistic Difference Equation

    The logistic difference equation can be made dimensionless and rewritten in the simpler form: Xn+1 = f (Xn) (1) if we introduce (a) Find the function f ; (Hint: you can denote ) (b) Consider the logistic map given by the equation (1) for all real X and for any a>1. i. Show that if Xn > 1 for...