Hey there! Sign in to join this conversationNew here? Join for free
    • Thread Starter
    Offline

    2
    ReputationRep:
    I have to use the chain rule to differentiate y=sin(t^2+9t+11)

    Is it just U=(t^2+9t+11) and Y=sin(U) ??
    Is this right? Why do i even have to use the chain rule for this case?
    Offline

    22
    ReputationRep:
    (Original post by ErniePicks)
    I have to use the chain rule to differentiate y=sin(t^2+9t+11)

    Is it just U=(t^2+9t+11) and Y=sin(U) ??
    Is this right? Why do i even have to use the chain rule for this case?
    Yes, that's correct, then we have that \displaystyle \frac{\mathrm{d}y}{\mathrm{d}t} = \frac{\mathrm{d}y}{\mathrm{d}u} \times \frac{\mathrm{d}u}{\mathrm{d}t} = \cos (u) \times \frac{\mathrm{d}}{\mathrm{d}t} (t^2 + 9t +11)
    Offline

    20
    ReputationRep:
    Yeah that's correct, why would you not use the chain rule? It is a function in a function.
    • Thread Starter
    Offline

    2
    ReputationRep:
    (Original post by Dinasaurus)
    Yeah that's correct, why would you not use the chain rule? It is a function in a function.
    I got 2t+9(cos(t^2+9t+11)) as the answer though, it doesn't look right...
    Offline

    20
    ReputationRep:
    (Original post by ErniePicks)
    I got 2t+9(cos(t^2+9t+11)) as the answer though, it doesn't look right...
    Most chain rule answers look messier than the original function given.
    Offline

    22
    ReputationRep:
    (Original post by ErniePicks)
    I got 2t+9(cos(t^2+9t+11)) as the answer though, it doesn't look right...
    If you mean (2t+9)\cos (t^2 + 9t+11) \neq 2t + 9(\cos (t^2 + 9+ 11)) (if you mean the former) then you're correct, if you mean the latter, then you're wrong.
    • Thread Starter
    Offline

    2
    ReputationRep:
    you are good human beings
    Offline

    17
    ReputationRep:
    (Original post by ErniePicks)
    I got (2t+9)(cos(t^2+9t+11)) as the answer though, it doesn't look right...
    just remember to bracket that term but other than that its perfect


    doesnt look "right" because sin(t^2+9t+11) is a weird looking function :laugh:

    Edit: i think there is an echo whoops
 
 
 
  • See more of what you like on The Student Room

    You can personalise what you see on TSR. Tell us a little about yourself to get started.

  • Poll
    Would you like to hibernate through the winter months?
    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
  • See more of what you like on The Student Room

    You can personalise what you see on TSR. Tell us a little about yourself to get started.

  • 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

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