Recent content by David Donald

I am having trouble doing this problem from my textbook... and have no idea how to doit. 1. Homework Statement I am having trouble doing this problem from my textbook... Show that the equation x + y - z + cos(xyz) = 0 can be solved for z = g(x,y) near the origin. Find dg/dx and dg/dy (dg/dx...

Hello, I am a 2nd year undergraduate maths student going into my third year who has been through.. Calc 1 Calc 2 Calc 3 or Multivariable Calculus Linear Algebra Differential Equations I bought two books Linear Algebra Done Right and Elementary Analysis: The Theory of Calculus I want to brush...

Homework Statement Verify that i2=-1 using (a+bi)(c+di) = (ac-bd)(ad+bc)i Homework Equations (a+bi)(c+di) = (ac-bd)(ad+bc)i The Attempt at a Solution I tried choosing coefficients so that it would be (i)(i) = (0 - 1)+(0+0)i = -1 so then I get i^2 = -1 But I was told that this was wrong and...

It's 100 volts, I'm not going to bother writing all the work out here since I just derived it on paper. My confusion just stemmed from the behavior of the inductor itself...

So the current would just then be 0 ? I(t) = E/R ( 1 - 1) (0) = (0)

Homework Statement Let's say I have a circuit such as the one above, and let's say the circuit has been open for a long time. How would I find the current through the inductor, the instant after closing the switch? and the voltage potential across the 40 mh inductor? Homework Equations...

I guess I'm confused because I have, derivatives on both sides when solving for Dx and Dy

I have very little Linear Algebra knowledge, I don't know if i could set up the linear system correctly |Dx| = |-Dy + 2x + 2y| |Dy| = |-2Dy + y + 3 |

Homework Statement dx/dt + dy/dt = 2x + 2y + 1 dx/dt + 2(dy/dt) = y + 3 Homework Equations The Attempt at a Solution Dx + Dy = 2x + 2y + 1 Dx + 2Dy = y + 3 --Rearranging---------------------------- Dx - 2x = -Dy + 2y + 1 Dx = -2Dy + y + 3 ---Factoring----------------------------- (D...

W is an amount that is getting withdrawed each year and K is a percentage based growth

So I have a diff eq dy/dx = ky - w where K and W are constant's I want to draw a phase portrait so i set ky - w = 0 and determine the expression equals 0 at y = w/k so I want to study the behavior of the solution greater w/k and less than w/k so I plug (2w/k) and (-2w/k) and check the...

Hello! so I'm working on a homework problem where I need to solve the diff equation dy/dt = ky - W where Y is the amount of money in a savings account W is a constant k is another constant (growing at a percentage) solving the diff equation I got y = W(1/k) + ((c)/(e^-kx)) now my question...

Homework Statement The Bracket BCD Is hinged at C and attached to a control cable at B. For the loading showm, determine the tension in the cable, the reaction at C. so after attempting this problem for about an hour and still not getting the right answer I decided to look up the solution...

I am trying to solve a homework problem that involves Work and friction but don't understand why if a force pulling upward on the object, the normal force becomes N = mg - Fsin(o) shouldn't it be N = mg + Fsin(o) since both forces are acting upwards? (the normal force and the force applied)

Homework Statement A 100 lb vertical force is applied to the end of a lever, which is attached to a shaft at O. Determine (a) the moment of the 100 lb force about O (b) the horizontal force applied at a that creates the same moment about O. Homework EquationsThe Attempt at a Solution I know...