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

    2
    ReputationRep:
    Name:  RenderedImage.jpg
Views: 28
Size:  317.8 KB

    Could someone please explain this to me?
    • Very Important Poster
    Online

    21
    ReputationRep:
    (Original post by razzy02)
    Name:  RenderedImage.jpg
Views: 28
Size:  317.8 KB

    Could someone please explain this to me?
    What is 81^(1/4), first of all? How can you work out what it is?

    Same logic for the 25 term

    Then see how to put that knowledge together
    • Thread Starter
    Offline

    2
    ReputationRep:
    (Original post by SeanFM)
    What is 81^(1/4), first of all? How can you work out what it is?

    Same logic for the 25 term

    Then see how to put that knowledge together
    So 81^(1/4) is 3, and 25 ^ (-1/2) is 50 and then I would multiply them together.
    Is this correct?
    Offline

    16
    ReputationRep:
    (Original post by razzy02)
    So 81^(1/4) is 3, and 25 ^ (-1/2) is 50 and then I would multiply them together.
    Is this correct?
    Not quite for the part in bold.

    If, like you correctly calculated,  81^{\frac{1} {4}} = \sqrt[4] {81} = 3
    Then, first of all what would  25^{\frac{1} {2}} be?
    • Thread Starter
    Offline

    2
    ReputationRep:
    (Original post by KaylaB)
    Not quite for the part in bold.

    If, like you correctly calculated,  81^{\frac{1} {4}} = \sqrt[4] {81} = 3
    Then, first of all what would  25^{\frac{1} {2}} be?
    It would be 5
    Offline

    16
    ReputationRep:
    (Original post by razzy02)
    It would be 5
    Correct , and what does a negative power mean?
    • Thread Starter
    Offline

    2
    ReputationRep:
    (Original post by KaylaB)
    Correct , and what does a negative power mean?
    You see that's where I begin to struggle with the question! would I have to flip the fraction upside down?
    Offline

    16
    ReputationRep:
    (Original post by razzy02)
    You see that's where I begin to struggle with the question! would I have to flip the fraction upside down?
    Ah I see! For negative indices, it means you do 1 over the x value without the negative sign. It doesn't make much sense when I'm typing it, so I apologise, hopefully this image will show you what I mean


    So in the same way as the graphic above. How else can  25^{-\dfrac{1} {2}} be written?
    • Thread Starter
    Offline

    2
    ReputationRep:
    (Original post by KaylaB)
    Ah I see! For negative indices, it means you do 1 over the x value without the negative sign. It doesn't make much sense when I'm typing it, so I apologise, hopefully this image will show you what I mean


    So in the same way as the graphic above. How else can  25^{-\dfrac{1} {2}} be written?
    Thank you so much!! So it would be 1/25^1/2?
    Offline

    16
    ReputationRep:
    (Original post by razzy02)
    Thank you so much!! So it would be 1/25^1/2?
    No problem :hat2:

    Yes it would be

    So, if we already know what  25^{\frac{1} {2}} is equal to, then what is  25^{-\frac{1} {2}} = \dfrac{1} {25^\frac{1} {2}} ?
    • Thread Starter
    Offline

    2
    ReputationRep:
    (Original post by KaylaB)
    No problem :hat2:

    Yes it would be

    So, if we already know what  25^{\frac{1} {2}} is equal to, then what is  25^{-\frac{1} {2}} = \dfrac{1} {25^\frac{1} {2}} ?
    1/5!!
    Offline

    16
    ReputationRep:
    (Original post by razzy02)
    1/5!!
    Yes! Well done! :clap2:

    So finally, can you now tell me what  81^{\frac{1} {4}} \times 25^{-\frac{1} {2}} is equal to? :holmes:
    • Thread Starter
    Offline

    2
    ReputationRep:
    (Original post by KaylaB)
    Yes! Well done! :clap2:

    So finally, can you now tell me what  81^{\frac{1} {4}} \times 25^{-\frac{1} {2}} is equal to? :holmes:
    That would be 3 x 1/5 = 0.6 xx
    Thank you so much for all your help!!!
    Offline

    16
    ReputationRep:
    (Original post by razzy02)
    That would be 3 x 1/5 = 0.6 xx
    Thank you so much for all your help!!!
    That's correct, good job! :clap2::clap2:

    Glad that I could be of assistance :hat2:
    Offline

    0
    ReputationRep:
    to work out something to the power of 1/4 you simply find the square root, then find the square root again. eg 81=9=3.

    when finding out a negative power you need to make it positive by flipping the fraction so there its 25 to the power of -1/2 changes to just 1/2 meaning square root of 25 which is 5.

    Then multiply 3 and 5 to get the final answer.
    Offline

    16
    ReputationRep:
    (Original post by keeleighgeorge)
    to work out something to the power of 1/4 you simply find the square root, then find the square root again. eg 81=9=3.

    when finding out a negative power you need to make it positive by flipping the fraction so there its 25 to the power of -1/2 changes to just 1/2 meaning square root of 25 which is 5.

    Then multiply 3 and 5 to get the final answer.
    I'm afraid that isn't correct. See above for how to approach this question
 
 
 
  • 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
    What newspaper do you read/prefer?
    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.