Join TSR now and get all your revision questions answeredSign up now

The function lnx Watch

    • Thread Starter
    Offline

    0
    ReputationRep:
    Is this right?

    e^2x+1 = 2
    2x +1 = ln 2
    x = 0.5 ln( 2- 1)

    I though for the last step:

    x = 0.5 (ln(2) -1)

    with the one outside the ln brakets?
    Offline

    1
    ReputationRep:
    You are correct. The last step is x = 0.5 (ln(2)-1)
    • Thread Starter
    Offline

    0
    ReputationRep:
    (Original post by CharlieBoardman)
    You are correct. The last step is x = 0.5 (ln(2)-1)
    Thats what is thought but the mark sheme says this

    0.5 ln( 2- 1)
    Offline

    2
    (Original post by nazgul60)
    Thats what is thought but the mark sheme says this

    0.5 ln( 2- 1)
    That's wrong.
    Offline

    2
    ReputationRep:
    (Original post by nazgul60)
    Thats what is thought but the mark sheme says this

    0.5 ln( 2- 1)
    It is wrong because that gives 0.5ln(1) = 0 and this can be easily disproved by substituting x=0 into the initial equation.
    • Thread Starter
    Offline

    0
    ReputationRep:
    (Original post by Micky76)
    It is wrong because that gives 0.5ln(1) = 0 and this can be easily disproved by substituting x=0 into the initial equation.
    Thats what i thought but just needed to be confident. Thanks!
    Offline

    3
    ReputationRep:
    Am I just being stupid or isn't x=0 the answer?
    • Study Helper
    Offline

    0
    ReputationRep:
    e^{2x+1}=2

    or

    e^{2x}+1=2
    Offline

    2
    ReputationRep:
    (Original post by BabyMaths)
    e^{2x+1}=2

    or

    e^{2x}+1=2
    Is it not multiplied by e instead of the +1?
    • Thread Starter
    Offline

    0
    ReputationRep:
    (Original post by BabyMaths)
    e^{2x+1}=2


    that one
    Offline

    2
    ReputationRep:
    (Original post by BabyMaths)
    e^{2x+1}=2

    or

    e^{2x}+1=2
    Sorry, my bad in the interpretation of your post.
    • Study Helper
    Offline

    0
    ReputationRep:
    (Original post by nazgul60)
    that one
    In that case x=\frac{1}{2}(-1+\ln 2) as you thought.
    Offline

    1
    ReputationRep:
    (Original post by nazgul60)
    Thats what is thought but the mark sheme says this

    0.5 ln( 2- 1)
    Sometimes mark schemes have mistakes in them. Don't worry - you are correct!
    Offline

    2
    ReputationRep:
    (Original post by nazgul60)
    that one
    Then you are right/mark scheme is wrong.

    probably just a typing error by a clerk who doesn't know to be careful with these things.
 
 
 
Poll
How are you feeling about Results Day?
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

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