Turn on thread page Beta
    • Thread Starter
    Offline

    2
    ReputationRep:
    Hi i'm having trouble solving these coupled differential equations... Could you help me out please?

    \frac{dx}{dt}=-x+y+cos(t)
    \frac{dy}{dt}=x-y+sin(t)

    many thanks
    Offline

    10
    ReputationRep:
    Differentiate one with respect to t and sub in the other one to get an ODE
    • Thread Starter
    Offline

    2
    ReputationRep:
    thank you, i had considered that. however the question requires me to eliminate y and \frac{dy}{dt}

    first and then solved the second order odes that follow any ideas?
    • Thread Starter
    Offline

    2
    ReputationRep:
    so. I've differentiated the first one again and substituted the second one into it giving me:
    \frac{d^2x}{dt^2}+2\frac{dx}{dt}-2x=cos(t)

    the characteristic equation being:
    m^2+2m-2=0

    m=-1+-sqrt3

    what do i do after finding the particular integral?
    Offline

    7
    ReputationRep:
    Same as normal I would assume, let x = pcost + qsint then differentiate twice and substitute in to find p and q.
 
 
 
Reply
Submit reply
Turn on thread page Beta
Updated: October 21, 2006

University open days

  • University of Bradford
    All faculties Undergraduate
    Wed, 21 Nov '18
  • Buckinghamshire New University
    All Faculties Postgraduate
    Wed, 21 Nov '18
  • Heriot-Watt University
    All Schools Postgraduate
    Wed, 21 Nov '18
Poll
Black Friday: Yay or Nay?
Useful resources

Make your revision easier

Maths

Maths Forum posting guidelines

Not sure where to post? Read the updated guidelines here

Equations

How to use LaTex

Writing equations the easy way

Equations

Best calculators for A level Maths

Tips on which model to get

Student revising

Study habits of A* students

Top tips from students who have already aced their exams

Study Planner

Create your own Study Planner

Never miss a deadline again

Polling station sign

Thinking about a maths degree?

Chat with other maths applicants

Can you help? Study help unanswered threads

Groups associated with this forum:

View associated groups

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Write a reply...
Reply
Hide
Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.