Help putting differential equations into matrix form

hajjar0415
Messages
2
Reaction score
0

Homework Statement



Hello, I am trying to put the following equations into matrix form in order to solve the system. If anyone could please explain to me how to do it or show me an example it would be awesome.

All material given in question:

For the system of inhomogeneous differential equations,
dx/dt = 5x-y+2

dy/dt = x + 3y – 4t

and the initial condition, x(0)=1 and y(0)=2.

a)Arrange the system into matrix form
b)Find the diagonal or Jordan form of the system matrix
c)Write the general solution in the form of the matrix exponential
d)Use the initial condition to find the solution x(t) and y(t)

Thanks for any help

Homework Equations





The Attempt at a Solution



I am aware that the matrix has to be square in order to proceed.

What i have so far is:

[5 -1 0 ] [x] + [2]
[1 3 -4 ] [y] + [0]
[0 0 0 ] [t] + [0]

The -4t is what is throwing me off because there is no dt/dt equation given so i have put all 0's in the matrix.
 
Physics news on Phys.org
##t## is your independent variable. Write your system in the form$$
\begin{bmatrix} x'\\y'
\end{bmatrix}=
\begin{bmatrix}
a&b\\c&d
\end{bmatrix}
\begin{bmatrix}
x\\y
\end{bmatrix}+
\begin{bmatrix}
f(t)\\g(t)
\end{bmatrix}$$
 
So would the matrix form be:

5 -1 , x + 2
1 3 ,y + -4t

thanks for the help
 
hajjar0415 said:
So would the matrix form be:

5 -1 , x + 2
1 3 ,y + -4t

thanks for the help

I showed you one form. But yours isn't like mine because you have no derivatives nor equals signs. Surely your text shows you what form to use.
 
There are two things I don't understand about this problem. First, when finding the nth root of a number, there should in theory be n solutions. However, the formula produces n+1 roots. Here is how. The first root is simply ##\left(r\right)^{\left(\frac{1}{n}\right)}##. Then you multiply this first root by n additional expressions given by the formula, as you go through k=0,1,...n-1. So you end up with n+1 roots, which cannot be correct. Let me illustrate what I mean. For this...
Back
Top