Quantcast

A community for students. Sign up today!

Here's the question you clicked on:

55 members online
  • 0 replying
  • 0 viewing

estudier

  • 2 years ago

(5^3 +1) / (5^3 +4^3) = (5+1)/(5+4) (67^3 + 41^3) /(67^3 + 26^3) = (67 +41)/(67+26) So cancelling 3's works?

  • This Question is Closed
  1. queenchatter
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    yes

  2. Maledant
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    For the first one, no, for the second one, yes

  3. estudier
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 1

    Works for first and second, question is why?

  4. Maledant
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Oh, let me correct that. Was wrong about my answer. forgot that 1 does not change even if cubed.

  5. Maledant
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    So correcting my self, yes, because \[1^3 = 1\]

  6. estudier
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 1

    124^3 + 43^3/ 124^3 +81^3 = 124 +43/124 +81

  7. Jonask
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 1

    this is working because of the factorisation of\[x^3+y^3\]

  8. Jonask
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 1

    \[\frac{ x^3+y^3 }{ x^3+z^3 }=\frac{ (x+y)(x^2-xy+y^2) }{ (x+z)(x^2-zx+ z^2)}\] which should equal\[\frac{ x+y }{ x+z }\] if and only if \[x^2-xy+y^2=x^2-zx+z^2\] \[x(y-z)=y^2-z^2\]

  9. Jonask
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 1

    \[5(1-4)=1^2-4^2\] true

  10. Jonask
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 1

    \[67(41-26)=41^2-26^2\] IS THAT TRUE

  11. estudier
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 1

    Yes, that's true, what's the general rule, though?

  12. Jonask
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 1

    this should be true\[x=y-z\]

  13. estudier
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 1

    (n^3 + a^3)/(n^3 +b^3) where a+b = n

  14. Jonask
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 1

    this should be true \[x=y+z\] the top one not true, a+b=n

  15. estudier
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 1

    1 + 4 = 5 41 +26 =67 43 +81 = 124 Still haven't (quite) proved it though....

  16. Jonask
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 1

    \[x(y-z)=y^2-z^2=(y-z)(y+z)\] \[x=y+z\] but \[y \neq z\]

  17. Jonask
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 1

    1 + 4 = 5 41 +26 =67 43 +81 = 124 Still haven't (quite) proved it though.... ????

  18. estudier
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 1

    K, you sub in what u r saying into the expansion of the cubes and then the denominator and numerator are equal, right?

  19. Jonask
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 1

    right,equal yes and without cubes

  20. estudier
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 1

    Cool.

  21. Not the answer you are looking for?
    Search for more explanations.

    Search OpenStudy
    • Attachments:

Ask your own question

Ask a Question
Find more explanations on OpenStudy

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.