# Recent content by inter060708

1. ### Backward Impedance Matching

Homework Statement https://scontent-lax3-1.xx.fbcdn.net/v/t34.0-12/14804959_10155526179417281_80533891_n.png?oh=649ee14155ac558b21c6553f003e418b&oe=5809EAA0 Homework Equations The Attempt at a Solution 1) I determined the input impedance of the first transmission line (Zin1). 2) I calculated...
2. ### Problem with open circuit

Thank you, Dick
3. ### Problem with open circuit

Okay. In that case, there's no current in the bottom wire either? (Nodes connecting the negative ends of 7 and 2 ohm resistors)
4. ### Problem with open circuit

Homework Statement Find the value of v1, v2, vab, vbc, vca. See picture Homework Equations Kirchoff's Law The Attempt at a Solution Is it true that both current through 3 and 4 ohm resistors are zero? The way I think of this is if they aren't zero, there would be charge building up at a...
5. ### Proving subset of a Nullspace

Ok I think I got it. to prove that if ##x \in N(A)## then ##x \in N(A^t A)##. ##x \in N(A)##. By definition, ##Ax = 0## therefore ##A^t A x = 0## which means ##x \in N(A^t A)## as well. Therefore ##N(A) \subset N(A^t A)##. Thanks a lot jbunniii.
6. ### Proving subset of a Nullspace

x ε N(A) iff Ax = 0 and since A^t A x = 0 then x ε N(A^t A). Therefore x belongs to both N(A) and N(A^t A). Is this correct?
7. ### Proving subset of a Nullspace

I need to show that elements in X also belongs to Y.
8. ### Proving subset of a Nullspace

A^t A x= 0 and how do I justify the subset part?
9. ### Proving subset of a Nullspace

Homework Statement Given matrix A (size m x n), prove N(A) is subset of N( A^t A). A^t is matrix A transposed. Homework Equations The Attempt at a Solution My assumption is m < n, using definition of nullspace, I ended up with N( A^t A) = a set of zero vector, while N(A) is...
10. ### Find work done in stretching rubber band

I am sorry, but in this case, are you saying that my prof's limit of integration is correct? I understand that you need reference length for the force to be acting, but putting the initial limit of integration as something other than 0 would mean that you have stretched it beyond its natural...
11. ### Find work done in stretching rubber band

No substitution were made. He did it everything the same way except for the limits of integration. How can I explain to him?
12. ### Find work done in stretching rubber band

Homework Statement Please see attachment. Homework Equations The Attempt at a Solution Not really a homework problem. This is 1 of my exam question which I believe I had the right answer but my professor insists that he has the right one. I started by equating work done, W =...
13. ### Difference between unique solution and particular solution

Homework Statement For 1st order linear ordinary differential equation, how do "unique solution" and "particular solution" differ? Homework Equations if dy/dx = f(x,y) and partial f(x,y) with respect to y are both continuous, then there exists a unique solution within a region R...
14. ### Separable Differential Equation Question

Homework Statement dy/dx = (y^2 - 1)/ (x^2 - 1) with initial condition y(2) = 2 Why is y = 1 and/or y= -1 not solutions? Homework Equations The Attempt at a Solution I am actually able to solve this differential equation but when I separate the equation according to x and y...
15. ### Substituting Integration with trigonometric function

Alright. Thank you so much, you guys.