understanding differential equations.

Question

+5

871

5

+1313

Tried serveral times with a failed method.

d/R+R=1, R(1)=0.1. The answer provided is R=1-0.9e^1-y

For dy/dt=y/3+t would i need to use the substitution method?

math

Stu Aug 17, 2014

+33614

+15

Best Answer

The following should help:

ODE1

ODE2

Note: Use integration by parts to do the integral I left to you: Let u = t and dv = e^-(1/3)tdt. Then ∫udv=uv-∫vdu

Alan Aug 17, 2014

Alan · Answer 1 · 2014-08-17T11:01:06

The following should help:

ODE1

ODE2

Note: Use integration by parts to do the integral I left to you: Let u = t and dv = e^-(1/3)tdt. Then ∫udv=uv-∫vdu

AzizHusain · Answer 2 · 2014-08-17T08:26:26

I am not sure about the first one, what is the d/R?

Also, yes, you need to use the substitution method for the second one I believe.

Stu · Answer 3 · 2014-08-17T01:22:54

I entered it poorly. The equation should have been dR/dy +R equals 1 with the initial conditions as above. Is it the same now as your reply Alan?

Alan · Answer 4 · 2014-08-17T02:31:55

Yes, that's what I assumed.

Stu · Answer 5 · 2014-09-22T07:23:50

Thanks. I got that when I did it or close. I probahbly lost a sign somewhere in my calculations. cheers.