Turn on thread page Beta
    • Thread Starter
    Offline

    10
    ReputationRep:
    I have this equation:
    Name:  Capture.PNG
Views: 10
Size:  3.0 KB
    Where u is a function, ct and cnt are variables and ubar a constant.
    And need to find:
    Attachment 726832
    How would I start this?
    • Community Assistant
    Offline

    20
    ReputationRep:
    Community Assistant
    (Original post by DQd)
    I have this equation:
    Name:  Capture.PNG
Views: 10
Size:  3.0 KB
    Where u is a function, ct and cnt are variables and ubar a constant.
    And need to find:
    Attachment 726832
    How would I start this?
    Just differentiate through by c_{nt}. This means that for the first term you must use the chain rule.
    • Community Assistant
    • Study Helper
    Offline

    20
    ReputationRep:
    Community Assistant
    Study Helper
    I don't like the look of that equation...
    • Thread Starter
    Offline

    10
    ReputationRep:
    (Original post by RDKGames)
    Just differentiate through by c_{nt}. This means that for the first term you must use the chain rule.
    Thanks, got the answer.
    Didn't think to split the first term.
    As an aside, is it incorrect to say the first term Name:  Capturetr.PNG
Views: 9
Size:  1.8 KB is equal to 0 because there is no cnt in 0.5u(ct)?
    • Community Assistant
    Offline

    20
    ReputationRep:
    Community Assistant
    (Original post by DQd)
    Thanks, got the answer.
    Didn't think to split the first term.
    As an aside, is it incorrect to say the first term is equal to 0 because there is no cnt in 0.5u(ct)?
    Yes that's incorrect.

    If you were to differentiate y^2=x w.r.t x, you'd say 2y\dfrac{dy}{dx} = 1 and not 0 = 1.

    If u(c_t) was constant, then yes the derivative would make it 0
    • Community Assistant
    Offline

    20
    ReputationRep:
    Community Assistant
    (Original post by Notnek)
    I don't like the look of that equation...
    What's wrong with it?
    • Thread Starter
    Offline

    10
    ReputationRep:
    (Original post by RDKGames)
    Yes that's incorrect.

    If you were to differentiate y^2=x w.r.t x, you'd say 2y\dfrac{dy}{dx} = 1 and not 0 = 1.

    If u(c_t) was constant, then yes the derivative would make it 0
    Got it.
    The solutions only have one step:
    Name:  Captureh.PNG
Views: 10
Size:  3.0 KB
    Is there any slightly different method to solve this or do you think it's just the method you stated but multiplied by dcnt
    • Community Assistant
    Offline

    20
    ReputationRep:
    Community Assistant
    (Original post by DQd)
    Got it.
    The solutions only have one step:
    Name:  Captureh.PNG
Views: 10
Size:  3.0 KB
    Is there any slightly different method to solve this or do you think it's just the method you stated but multiplied by dcnt
    Yes, indeed it is the exact same method as I said but they made an extra step afterwards of multiplying through by d{c_{nt}}
    • Community Assistant
    • Study Helper
    Offline

    20
    ReputationRep:
    Community Assistant
    Study Helper
    (Original post by RDKGames)
    What's wrong with it?
    Ignore me.
 
 
 
Reply
Submit reply
Turn on thread page Beta
Updated: February 22, 2018
Poll
Do you think parents should charge rent?
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

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.