Solve System of Equations with Real Numbers

Join the discussion
Registration is free. Ask a follow-up in this thread, or start your own.
3 replies · 2K views
juantheron
Messages
243
Reaction score
1
Solve the following system of equations in real numbers:$\sqrt{x^2-2x+6}\cdot \log_{3}(6-y) =x$$\sqrt{y^2-2y+6}\cdot \log_{3}(6-z)=y$$\sqrt{z^2-2z+6}\cdot\log_{3}(6-x)=z .$
 
Physics news on Phys.org
Have you looked at (3,3,3) being a solution, not sure myself but it might work given the base of those logs.
 
Hello, jacks!

I agree with pickslides . . .

[tex]\text{Solve the following system of equations in real numbers:}[/tex]

. . [tex]\begin{array}{ccc}\sqrt{x^2-2x+6}\cdot \log_{3}(6-y) &=&x \\<br /> \sqrt{y^2-2y+6}\cdot \log_{3}(6-z) &=& y \\<br /> \sqrt{z^2-2z+6}\cdot\log_{3}(6-x)&=&z\end{array}[/tex]
Due to the symmetry, I assume that [tex]x = y = z.[/tex]

Then we have: .[tex]\sqrt{x^2-2x+6}\cdot \log_3(6-x) \:=\:x[/tex]

By inspection, we see that: .[tex]x\,=\,3.[/tex]
 
soroban said:
Hello, jacks!

I agree with pickslides . . .


Due to the symmetry, I assume that [tex]x = y = z.[/tex]

Then we have: .[tex]\sqrt{x^2-2x+6}\cdot \log_3(6-x) \:=\:x[/tex]

By inspection, we see that: .[tex]x\,=\,3.[/tex]
Symmetry only guarantees that any permutation of the values of x, y, z for a solution is also a solution.

Obviously x=y=z=3 is a solution, but symmetry alone does not force us to conclude that it is the only solution.

CB
 
Last edited: