Recent content by gabel

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

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?

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##

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

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...

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...

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

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 ?

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 adress this problem. Can get some help?

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}

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

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.

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]

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

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