Hey there! Sign in to join this conversationNew here? Join for free

C2 soloman paper B. integration with an infinate limity watch

    Offline

    22
    ReputationRep:
    (Original post by thefatone)
    so what about OP's question?

    i integrated and got 4x^ {\dfrac -{3}{2}}

    then i put values in and got

    [0]-[1.414]
    so is -1.414 correct as an answer?
    You've messed up your \LaTeX. The function is positive everywhere in the domain of integration; does a negative answer really make sense? You mean \sqrt{2}, not 1.414.
    Offline

    3
    ReputationRep:
    (Original post by Zacken)
    You've messed up your \LaTeX. The function is positive everywhere in the domain of integration; does a negative answer really make sense? You mean \sqrt{2}, not 1.414.
    better? i changed it

    oh ... i just used my calculator but yes  \sqrt 2

    so does that mean the area i got is below the x-axis?
    Offline

    22
    ReputationRep:
    (Original post by thefatone)
    better? i changed it

    oh ... i just used my calculator but yes  \sqrt 2

    so does that mean the area i got is below the x-axis?
    No, it means you integrated wrong.
    Offline

    3
    ReputationRep:
    (Original post by Zacken)
    No, it means you integrated wrong.
    aww s**t let's try again

    \dfrac{6}{x^ \frac {5}{2}} = 6x^{-\frac {5}{2}}

    so integrating

    \displaystyle \frac{6x^{-\frac{3}{2}}}{-\frac{3}{2}}

     -4x^{-\frac{3}{2}}

    subbing infinity gives 0

    subbing 2 in gives  -\left( \sqrt 2\right)

    [0]-[-\sqrt 2]

    so i get positive \sqrt 2????
    Offline

    22
    ReputationRep:
    (Original post by thefatone)
    ...
    Where'd the negative in the denominator go?
    Offline

    3
    ReputationRep:
    (Original post by Zacken)
    Where'd the negative in the denominator go?
    oh.... lemme change that
    Offline

    22
    ReputationRep:
    (Original post by thefatone)
    oh.... lemme change that
    Okay, it's fine now. Now do your limits and remember the negative signs.
    Offline

    3
    ReputationRep:
    (Original post by Zacken)
    Okay, it's fine now. Now do your limits and remember the negative signs.
    all better? (editied)
    Offline

    22
    ReputationRep:
    (Original post by thefatone)
    all better? (editied)
    Yes.
 
 
 
Poll
Do you agree with the PM's proposal to cut tuition fees for some courses?
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.