Recent content by Salt

OK I just saw this in my text (paraphrasing), y\left( t \right)=\int_{-\infty }^{t}{x\left( \tau \right)}d\tau therefore x\left( t \right)=\frac{dy}{dt} So y\left( t \right)=\int_{-\infty }^{t}{x\left( \tau \right)}d\tau is just like a non-definite integral? y\left( t...

I see equations of the form, y=\int_{-\infty }^{t}{F\left( x \right)}dx a lot in my texts. What exactly does it mean? From the looks of it, it just means there is effectively no lower bounds. I looked up improper integrals, but I can't say I really understand what is going on. So when...

Oh ... that would explain it. My textbook didn't put the absolute value brackets**. -_- Thanks. **Ya, it's not the best book, quite a few obvious typos, but it's easy enough to read. Should really get a more rigorous and accurate "second opinion" ...

Homework Statement OK, this is something that stumped me. Homework Equations \int_{}^{}{\frac{dZ}{ A^{2}-Z^{2}}} = - \int_{}^{}{\frac{dZ}{ Z^{2}-A^{2} }} Right? \int_{}^{}{\frac{dZ}{ A^{2}-Z^{2} }}=\; \frac{1}{2A}\ln \left\{ \frac{A+Z}{A-Z} \right\}+\mbox{C} \int_{}^{}{\frac{dZ}{...

Hmm ... Looks like my calculus really does suck. It was just written "like that" in the book. It probably assumes that I know how to solve it. >< Thanks.

simple integration question involving-infty "subscript" Homework Statement Been reading about signals, but my calculus skills have rusted (or never has been all that good in the first place). So ... Homework Equations Why does x(t) = \int^t_{-\infty} x'(\tau) \,d\tau ? The...

Thanks everyone. Sorry about the size, I attached a bigger one in this post. So from what I understand from reading the replies and scratching my head over the AND and IMPLIE truth tables. right side of 3) asserts : there exist a x such that it's a member of F and true for P(x)...

I have no idea how to type math symbols into here so it's all in the PNG attached. I'm probably kind of dumb for not getting this but... I understand that 1) & 3) are true. And the 2) is not right, as it means all x are members of F and true for P(x) when we mean all x that are members of...

Well I suppose then what Prof. Feynman does might be more along the lines of: Crude example: square implies: has 4 sides all sides are equal angle between 2 side is 90 2 connecting sides times one another gives you the area of the figure has 4 sides implies : square or...

Ah, nice. An example. :smile: At least now I know it's possible. Well, thank you everyone for their replys. This question actually came to me while I was browsing through Prof. Feynman - Character of Physical Law. In it he says that he does not remember all that much, what ever he...

Well, that does seem to be what I thought they are, with the addition view that it's they are the most fundamental. I was sort of thinking. if I know : { Axioms - A implies B B implies C C implies D theorem - therefore A implies D } later I forget : C implies D but...

Okey, this might be a silly question. I know that theorems are deduced logically from the axioms. But I was just wondering is it possible to deduce an axiom from the theorems? In another words work backward, assuming the required theorems are known.

cos(1)[sin(1)+sin(2)+..+sin(89)] =cos(1)[sin(1)+sin(2)+..+sin(89)+ sin(90) - sin(90)] =cos(1)[S - sin(90)] =cos(1)[S - 1] =cos(1)S - cos(1) if I'm right :-p