Hey! Sign in to get help with your study questionsNew here? Join for free to post

differential equation:

Announcements Posted on
AQA GCSE physics P1 unofficial mark scheme 05-05-2016
  1. Offline

    ReputationRep:
    i would like to know what your answer to this question is:

    Solve: dy/dx = Sqrt(y^2-1) with i.c. y(1)=1.

    i get one answer
    my book gets another mathematica gets another
    maple gets another

    if i exponentiate the solution, i get one for i can`t explicitly solve for y
    if i take the solution as being inverse hyperbolic, i (apparently according to Maple) get the wrong answer also
    (hyperbolicly, i get y(x) = Cosh(x)

    what am i missing (appart from a few grey cells this time of night!)
  2. Offline

    ReputationRep:
    Arccosh(y)=x-1 => y=Cosh(x-1) ? mathematica gets cosh(1-x)!!
  3. Offline

    ReputationRep:
    (Original post by Hasufel)
    Arccosh(y)=x-1 => y=Cosh(x-1) ? mathematica gets cosh(1-x)!!
    They're the same.

    cosh(x-1) = 0.5(e^x-1 + e^-x+1)

    cosh(1-x) = 0.5(e^-x+1 + e^x-1)
  4. Offline

    ReputationRep:
    cheers!

    best go to bed i suppose!

Reply

Submit reply

Register

Thanks for posting! You just need to create an account in order to submit the post
  1. this can't be left blank
    that username has been taken, please choose another Forgotten your password?
  2. this can't be left blank
    this email is already registered. Forgotten your password?
  3. this can't be left blank

    6 characters or longer with both numbers and letters is safer

  4. this can't be left empty
    your full birthday is required
  1. Oops, you need to agree to our Ts&Cs to register
  2. Slide to join now Processing…

Updated: June 21, 2012
TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

Today on TSR

AQA GCSE maths

Check the unofficial mark scheme

Poll
What date is the EU referendum on?
Useful resources

Make your revision easier

Maths

Maths Forum posting guidelines

Not sure where to post? Read here first

Equations

How to use LaTex

Writing equations the easy way

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
Study resources
Quick reply
Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.