Recent content by gabel

  1. G

    Undergrad Is $\lim_{\Delta x \to 0}f(x+\Delta x) \cdot \Delta x = 0$ True?

    I was told in general, so there must be som functions that does the oppeist?
  2. G

    Undergrad Is $\lim_{\Delta x \to 0}f(x+\Delta x) \cdot \Delta x = 0$ True?

    Thanks, but i really need to show the following if its possibole. ## \lim_{\Delta x \to 0} f(x_0 + \Delta x) \cdot \Delta x= k ## Where k, is a constant. Is there something i can say aboute f?
  3. G

    Undergrad Is $\lim_{\Delta x \to 0}f(x+\Delta x) \cdot \Delta x = 0$ True?

    Is the following true, if no is there som theory i can studdy? ##\lim_{\Delta x \to 0}f(x+\Delta x) \cdot \Delta x = 0##
    • gabel
    • Thread
    • Function Limit
    • Replies: 5
    • Forum: Calculus
  4. G

    Undergrad How to Handle Integral with dx Inside the Function?

    Mod note: edited to show what I said and the responses.
  5. G

    Undergrad How to Handle Integral with dx Inside the Function?

    If i have a f(x) = ax+b, given 3 points on f(x), the area from those points shood be zero. Since they will always be on a line. But what heppens if f(x) = sin(x), cos(x), x^2, etc? Some more details. Red :f(x) = x Blue:f(x) = x^2 A_2 = 0, A_1 = something small Now i want to move A_1 along...
  6. G

    Undergrad How to Handle Integral with dx Inside the Function?

    I'm using the shoelace formula (http://en.wikipedia.org/wiki/Shoelace_formula) for a triangle, and then letting x_1 = x - dx , x_2 = x, x_3 = x + dx y_1 = f(x-dx), y_2 = f(x), y_3 = f(x+dx). Aften cleanup I am left whit this dA = 2 f(x) dx + 0.5 | f(x-dx) | dx + 0.5 |f(x+da)|dxNB, latex is...
  7. G

    Undergrad How to Handle Integral with dx Inside the Function?

    I have to following expression: dA = 2 f(x) dx + 0.5 | f(x-dx) | dx + 0.5 |f(x+da)|dx
  8. G

    Undergrad How to Handle Integral with dx Inside the Function?

    Im working on a problem whit the follewing integral: I = \int|f(x+dx)dx| Im trying to use int by parts : t = x + dx \Rightarrow dt/dx = 1 + ddx/dx = ?, but i have no idee on what ddx/dx is? I think dx -> konstant? so ddx/dx = 1 ?
    • gabel
    • Thread
    • Dx Function Integral
    • Replies: 10
    • Forum: Calculus
  9. G

    A signal x(t) is bandlimited to B Hz

    A singal x(t) is bandlimited to B Hz. Show that that the signal x^{n}(t) is bandlimited to nB Hz. I have no idee on how to address this problem. Can get some help?
  10. G

    Therefore D_n=\frac{2}{\pi(1-4n^2)}

    Ok, this is where I am at now. But I am stuck once more. D_k = \frac{2 cos^2(n\pi)+sin(2\pi n)}{1-4n^2}
  11. G

    Therefore D_n=\frac{2}{\pi(1-4n^2)}

    Hmm, I am unsure on how to threat the variable n
  12. G

    Therefore D_n=\frac{2}{\pi(1-4n^2)}

    D_n=\frac{1}{\pi}\int_0^\pi\sin{(t)}\cdot e^{-i2nt}dt=\frac{2}{\pi(1-4n^2)} I have no idea on how they get from one side of the equation symbol to the other, can i get some tips and tricks ? I have try ed writing sint as an exp function, but i don't feel it gets me anywhere close.
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    How to Find the Unit Impulse Response h[n]?

    Find h[n], the unit impulse response of the system descrived by the following equation: y[n]+3y[n-1]+2y[n-2]=x[n]+3x[n-1]+3x[n-2] Can this be rewritten as?(n-->n+2) y[n+2]+3y[n+1]+2y[n]=x[n+2]+3x[n+1]+3x[n]
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    Detrmine the unit impulse response

    Homework Statement Find the unut impulse response h[n] of this system y[n+1]+2y[n]=x[n] Homework Equations I have no clue on how to slove this problem, som pointers would be nice. Thx
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    Undergrad Is the equality \sqrt[n]{ab}= \sqrt[n]{a}\sqrt[n]{b} true for complex numbers?

    -1=\sqrt[3]{-1}=(-1)^{1/3} = (-1)^{2/6} = ((-1)^2)^{1/3}=1^{1/3} = 1 How can this be?