# Thread: Linear systems of differential equations

1. ## Linear systems of differential equations

Find the general systems of differential equations. You must use the method that includes matrices, eigen values, and eigen vectors. Carefully identify all the important steps.

y1 = y1 + 4y2 - 2cos t

y2 = y1 + y2 - cos t + sin t

I'm sorry, but I can't figure out how to make this stuff work! I rermember how to do most of the steps, I think, but it isn't working together. This is a practice problem, but my teacher assured me that there will be one just like it on the test on Monday, April 30. Could someone please show me how to do this so that I will know how to work on like it on the test?!?!? Thank you.

2. Originally Posted by SoBeautiful
Find the general systems of differential equations. You must use the method that includes matrices, eigen values, and eigen vectors. Carefully identify all the important steps.

y1 = y1 + 4y2 - 2cos t

y2 = y1 + y2 - cos t + sin t

I'm sorry, but I can't figure out how to make this stuff work! I rermember how to do most of the steps, I think, but it isn't working together. This is a practice problem, but my teacher assured me that there will be one just like it on the test on Monday, April 30. Could someone please show me how to do this so that I will know how to work on like it on the test?!?!? Thank you.
Is there a mistake? Your equations simplify to:
y2 = (1/2)cos(t)
and
y1 = cos(t) - sin(t)
which are independent and don't need any special methods to solve. (Not to mention, they aren't even differential equations!)

-Dan

3. Originally Posted by SoBeautiful
Find the general systems of differential equations. You must use the method that includes matrices, eigen values, and eigen vectors. Carefully identify all the important steps.

y1 = y1 + 4y2 - 2cos t

y2 = y1 + y2 - cos t + sin t

I'm sorry, but I can't figure out how to make this stuff work! I rermember how to do most of the steps, I think, but it isn't working together. This is a practice problem, but my teacher assured me that there will be one just like it on the test on Monday, April 30. Could someone please show me how to do this so that I will know how to work on like it on the test?!?!? Thank you.
Do you mean:

d/dt(y1) = y1 + 4y2 - 2cos t

d/dt(y2) = y1 + y2 - cos t + sin t

RonL

4. ## clarification

The problem looks like y(1, 1) just like Integrals are set up. It looks like y from 1 to 1 and the second one looks like y from 2 to 1. I think maybe that is just a way to make it look different than the y's on the other side of the equation???

5. Originally Posted by SoBeautiful
The problem looks like y(1, 1) just like Integrals are set up. It looks like y from 1 to 1 and the second one looks like y from 2 to 1. I think maybe that is just a way to make it look different than the y's on the other side of the equation???
No the left hand sides are y_1 prime and y_2 prime, they are the derivatives
of y_1 and y_2.

RonL

6. Oh, ok that makes more sense. Do you think you could help me with the first few steps so that I know how to get started? Or maybe an outline of what exactly I am supposed to do for the problem?

7. I have a problem that looks a lot like this one for my next assignment

8. Thanks for the clarification on y1 and y2 prime, but I still am not sure that I will be able to work a problem like this on the test tomorrow, so if anyone could help me out with this one, I would REALLY appreciate it. Thanks.