# Recent content by tnutty

1. ### Diffy-Q question

Figured it out, thanks for looking.
2. ### Diffy-Q question

Homework Statement Consider the population model dP/dt = -P^2/50 + 2P for a species of fish in a lake. Suppose it is decided that fishing will be allowed, but it is unclear how many fishing licenses should be issued. Suppose the average catch of a fisherman with a license is 3 fish per...
3. ### Affine transformation proof

Oh, I should have read the question carefully. Thanks a lot.
4. ### Affine transformation proof

Homework Statement An affine transformation T : R^n --> R^m has the form T(x) = Ax + y, where x,y are vectors and A is an m x n matrix and y is in R^m. Show that T is not a linear transformation when b != 0. Homework Equations There are couple of useful definitions, but I think this one...
5. ### Boolean algebra

Make a truth table to see why. X can equal only 1 or 0 thus the truth table for x*x is below : -------- x x x*x 0 0 0 1 1 1 ------- As you see if X = 0, then X*X = 0 = X, and if X = 1, then X*X = 1 = X. Thus X*X = X
6. ### Basic Matrix Question

In the last row you have this : [0 0 0 0 1] which means this in equation form, 0X1 + 0X2 + 0X3 + 0X4 = 1, which means 0 = 1. This is impossible mathematically, right? Because a 0 cannot never equal 1, which means that the system is inconsistent, or no solution. So Yes you are correct as to...
7. ### Basic Matrix Question

Its ok, the problem is trying to make you think hard, but I think once you thought about the problem a little, you should then confirm it by solving the matrix.
8. ### Basic Matrix Question

well try to solve it out and see
9. ### Basic Matrix Question

Oh, wait see this : The original matrix : [3 -2 0 1 1] [1 2 -3 1 -1] [2 4 -6 2 0] realize that the last row is a multiple of row2. Lets scale the last row3 so we have : [3 -2 0 1 1] [1 2 -3 1 -1] [1 2 -3 1 0] Notice something there?
10. ### Basic Matrix Question

Oh wait, there are 3 equation, and 4 variables. Do you think we have enough information to solve this matrix?
11. ### Basic Matrix Question

The key thing is on row3.
12. ### Quick question about matrix operations.

Ok, I will search for it. Thanks.
13. ### Quick question about matrix operations.

>>"What I have done is replace the 2nd equation by itself + 1 times the first equation." See thats the part thats bugging me. From middle school I have took that method as granted. Do you think that there if a formal proof of why that method would work? Or is it just drawn from intuitive reason...
14. ### Quick question about matrix operations.

Say there are these systems of equations : x - 2y + z = 0 2y - 8z = 8 -4x + 5y + 9z = -9 In matrix form, it can be represented like this : -- [1 -2 1 0] < -- row 1 [0 2 -8 8] < -- row 2 [-4 5 9 -9] < -- row 3 When we do elementary row operations, say on row3 = row3 +...
15. ### Findin largest volume

A*z = 2z(xy+xz+yz) V = xyz x = V/yz P/4 = x+y+z P/4 - x - y = z A*z = 2z(xy+xz+yz) A( P/4 - x - y ) = 2(P/4 - x -y) ( V/z + V/y + yz ) is that right? For a rectangular box, we could compute the area of one size and multiply by its depth to get the volume no? I am...