MHB Integer ordered pairs in logarithmic equation

AI Thread Summary
The discussion centers on finding integer ordered pairs (x, y, z) that satisfy a set of logarithmic equations. The constraints indicate that x, y, and z must be less than 6, leading to the transformation of the logarithmic terms into fractions involving square roots. A participant suggests that the only integer solution may be the trivial case where x, y, and z all equal 3, based on the nature of logarithmic functions. The conversation highlights the complexity of the equations and the challenge in determining additional solutions. Ultimately, the focus remains on the potential uniqueness of the solution at (3, 3, 3).
juantheron
Messages
243
Reaction score
1
no. of integer ordered pairs of $(x,y,z)$ in

$ \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 $

My approach :: Here $6-x,6-y,6-z>0$. So $x,y,z<6$

Now $\displaystyle \log_{3}(6-y) = \frac{x}{\sqrt{x^2-2x+6}}=\frac{x}{\sqrt{(x-1)^2+5}}$

and $\displaystyle \log_{3}(6-z) = \frac{y}{\sqrt{y^2-2y+6}}=\frac{y}{\sqrt{(y-1)^2+5}}$

and $\displaystyle \log_{3}(6-x) = \frac{z}{\sqrt{z^2-2z+6}}=\frac{z}{\sqrt{(z-1)^2+5}}$

How can I calculate after that.

Help please

Thanks
 
Mathematics news on Phys.org
Re: integer ordered pairs in logarithmic equation

I don't have a reference for this, but I guess that if $n$ is an integer then $\log_3n$ is transcendental unless $n$ is a power of $3$. If so, then the only solution to those equations must be the obvious one $x=y=z=3$.
 
Seemingly by some mathematical coincidence, a hexagon of sides 2,2,7,7, 11, and 11 can be inscribed in a circle of radius 7. The other day I saw a math problem on line, which they said came from a Polish Olympiad, where you compute the length x of the 3rd side which is the same as the radius, so that the sides of length 2,x, and 11 are inscribed on the arc of a semi-circle. The law of cosines applied twice gives the answer for x of exactly 7, but the arithmetic is so complex that the...
Is it possible to arrange six pencils such that each one touches the other five? If so, how? This is an adaption of a Martin Gardner puzzle only I changed it from cigarettes to pencils and left out the clues because PF folks don’t need clues. From the book “My Best Mathematical and Logic Puzzles”. Dover, 1994.
Back
Top