Can You Solve These Unique System of Equations?

  • Context: High School 
  • Thread starter Thread starter anemone
  • Start date Start date
anemone
Gold Member
MHB
POTW Director
Messages
3,851
Reaction score
115
Here is this week's POTW:

-----

Find all positive real solutions to the following system of solution:

$x^3+y^3+z^3=x+y+z$

$x^2+y^2+z^2=xyz$

-----

Remember to read the https://mathhelpboards.com/showthread.php?772-Problem-of-the-Week-%28POTW%29-Procedure-and-Guidelines to find out how to https://mathhelpboards.com/forms.php?do=form&fid=2!
 
Physics news on Phys.org
I apologize as I just realized the reply to this POTW #413 has gone amiss.

I just checked and no one answered to this POTW. (Sadface) Nevertheless, you can refer to the suggested solution by other below:

We have $xyz=x^2+y^2+z^2>Y^2+z^2\ge 2yz$. Hence $x>2$ and $x^3>x$. Similarly, $y^3>y$ and $z^3>z$. Adding them up gives $x^3+y^3+z^3>x+y+z$ and this contradicts to what is given and hence, there are no solutions to the system.
 

Similar threads

  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 1 ·
Replies
1
Views
1K
  • · Replies 1 ·
Replies
1
Views
2K