1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Quick question: x^2-y^2=16 (find x)

  1. Feb 22, 2017 #1
    1. The problem statement, all variables and given/known data
    x^2-y^2=16
    isolate the variable x

    2. Relevant equations
    square roots

    3. The attempt at a solution
    x^2=y^2+16

    x=y+4?
     
  2. jcsd
  3. Feb 22, 2017 #2

    BvU

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    Quick answer: No.
    Because your ##x^2 = (y+4)^2 \ne y^2+16 ##
     
  4. Feb 22, 2017 #3
    so whats the answer
     
  5. Feb 22, 2017 #4
    if i squared both sides it would just be the individual answer
     
  6. Feb 22, 2017 #5

    BvU

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    What's the full problem statement ? 'Isolate' doesn't sound like a question with an answer ...
     
  7. Feb 22, 2017 #6
    that was the problem..it just said isolate the variable x..
     
  8. Feb 22, 2017 #7
    NO! This is a fundamental mistake. ##\sqrt{a+b} \neq \sqrt{a} +\sqrt{b}##
     
  9. Feb 22, 2017 #8
    Isolate probably means solve for x in terms of y.
     
  10. Feb 22, 2017 #9
    said something like it is understood to be positive or something like that
     
  11. Feb 22, 2017 #10
    we were solving equations where you square both sides
     
  12. Feb 22, 2017 #11

    BvU

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    In that case you are done when you write ##x^2 = y^2 + 16 ## : it has x in isolation on the left hand side of the ##=## sign.
     
  13. Feb 22, 2017 #12
    it cant be a square
     
  14. Feb 22, 2017 #13
    • Poster has been reminded (too late) not to post answers to schoolwork questions on the PF
    So the answer is just ##x = \sqrt{y^2 + 16}## NOT ##y+4##
     
  15. Feb 22, 2017 #14

    BvU

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    Rapid fire of posts from three sides ...

    Ok, semantics: isolate means write it so that it says ## x = ##

    What do you have to keep in mind when going from ##x^2 = ... ## to ## x = ... ## ?
     
  16. Feb 22, 2017 #15
    why doesnt that reduce?
     
  17. Feb 22, 2017 #16

    BvU

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    Watch out MM ! PF hates direct answers. it ruins the learning experience :smile:
     
  18. Feb 22, 2017 #17
    learning experience means frustration and anger and deletion of account for me...
     
  19. Feb 22, 2017 #18
    Let's keep it cool. What's ##(a+b)^2##?
     
  20. Feb 22, 2017 #19
  21. Feb 22, 2017 #20

    BvU

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    It does reduce, but you have to be careful...
    I recognise the frustration and anger. Don't get carried away, sit back and think a bit now and then before firing of another post and the 'deletion of account' may be replaced by 'satisfaction from deeper udnerstanding' :smile:
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: Quick question: x^2-y^2=16 (find x)
  1. 2^x=x^2+7 Find x (Replies: 2)

Loading...