Quantcast

Got Homework?

Connect with other students for help. It's a free community.

  • across
    MIT Grad Student
    Online now
  • laura*
    Helped 1,000 students
    Online now
  • Hero
    College Math Guru
    Online now

Here's the question you clicked on:

55 members online
  • 0 replying
  • 0 viewing

johnny101 Group Title

1

  • 9 months ago
  • 9 months ago

  • This Question is Closed
  1. Easyaspi314 Group Title
    Best Response
    You've already chosen the best response.
    Medals 2

    As you are correct, x^2 - 2x has no inverse. BUT, if you restrict the domain, it would have an inverse.

    • 9 months ago
  2. Easyaspi314 Group Title
    Best Response
    You've already chosen the best response.
    Medals 2

    What we mean "it has no inverse"...that when you find the inverse, it will not be a function. So we say it has no inverse.

    • 9 months ago
  3. johnny101 Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    Ok thankyou that's what I thought, its a multiplce choice homework but I was confused because it can and cant have one

    • 9 months ago
  4. jdoe0001 Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    hmmm if you complete the square on the inverse, I do get an inverse function

    • 9 months ago
  5. Easyaspi314 Group Title
    Best Response
    You've already chosen the best response.
    Medals 2

    Can you demonstrate that?

    • 9 months ago
  6. jdoe0001 Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    one sec

    • 9 months ago
  7. johnny101 Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    x^2-x2 is a parabola graph therefore passes vertical line test and has inverse?

    • 9 months ago
  8. johnny101 Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    2x*

    • 9 months ago
  9. Easyaspi314 Group Title
    Best Response
    You've already chosen the best response.
    Medals 2

    Johnny.......you can find the inverse of x^2 - 2...no one is doubting that...but the inverse will not be a function..we call that the function not being "invertible".

    • 9 months ago
  10. johnny101 Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    so the question is determine if the function have an inverse f^-1, so in that regards it does? Now im confused

    • 9 months ago
  11. jdoe0001 Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    hmmm

    • 9 months ago
  12. Easyaspi314 Group Title
    Best Response
    You've already chosen the best response.
    Medals 2

    Johnny...that language is a very touchy area...many textbooks say that it does not have an inverse.....other textbooks say it has an inverse, whose inverse is not a function. It really is a question of symmantics. So a question has to worded very carefully to accomodate the many texts out there.

    • 9 months ago
  13. jdoe0001 Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    ahemm, I see.... the inverse expression I should call it, will not meet the criterion of a "function" since it'd be a horizontal parabola and thus not a function that will pass the vertical line test

    • 9 months ago
  14. Easyaspi314 Group Title
    Best Response
    You've already chosen the best response.
    Medals 2

    Agree...

    • 9 months ago
  15. Easyaspi314 Group Title
    Best Response
    You've already chosen the best response.
    Medals 2

    But, everyone will agree that if we have a function f(x) = x^2 , and we restrict the domain to the positive real numbers, then the function has an inverse, no if's and's or but's.

    • 9 months ago
  16. Easyaspi314 Group Title
    Best Response
    You've already chosen the best response.
    Medals 2

    Its inverse will be + sqrt(x)

    • 9 months ago
  17. johnny101 Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    so for the sake of a multiple choice homework, worded does it contain the function f^-1, x^2-2x does not because it then becomes a horizontal parabola i.e failing the vertical line test?

    • 9 months ago
  18. jdoe0001 Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    notice the picture, the "red inverse" would not pass the vertical line test

    • 9 months ago
  19. johnny101 Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    thanks!

    • 9 months ago
  20. Easyaspi314 Group Title
    Best Response
    You've already chosen the best response.
    Medals 2

    I prefer not to answer that question as I do not know which textbook you are using and how the author feels about the issue. But, I can tell you, that on a national exam, etc.. such a question would have to be worded so carefully as to accomodate all textbboks.

    • 9 months ago
  21. Easyaspi314 Group Title
    Best Response
    You've already chosen the best response.
    Medals 2

    Why not ask your teacher?

    • 9 months ago
  22. johnny101 Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    1 quick question, does it matter if its f(x) = x^2-2x or f(y)= x^2-2x?

    • 9 months ago
  23. jdoe0001 Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    \(\bf y = x^2-2x\qquad inverse\implies x = y^2-2y\\ \quad \\ x = y^2-2y+1-1\implies x = (y-1)^2-1\implies \sqrt{x+1}+1=y\)

    • 9 months ago
  24. Easyaspi314 Group Title
    Best Response
    You've already chosen the best response.
    Medals 2

    Again, thats a touchy matter...so I prefer to stay away from there; I dont want to mislead you, as I dont know your teachers' preferences, books style, etc.

    • 9 months ago
  25. jdoe0001 Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    @johnny101 so though you can simplify it and solve for "y", the resulting expression doesn't not meet the criterion of a "function", thus is not a function per se, thus no inverse \(\bf function\)

    • 9 months ago
  26. johnny101 Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    alright understood

    • 9 months ago
    • Attachments:

See more questions >>>

Your question is ready. Sign up for free to start getting answers.

spraguer (Moderator)
5 → View Detailed Profile

is replying to Can someone tell me what button the professor is hitting...

23

  • Teamwork 19 Teammate
  • Problem Solving 19 Hero
  • You have blocked this person.
  • ✔ You're a fan Checking fan status...

Thanks for being so helpful in mathematics. If you are getting quality help, make sure you spread the word about OpenStudy.

This is the testimonial you wrote.
You haven't written a testimonial for Owlfred.