System of Equations: Find Triples $(x,y,z)$

In summary, a system of equations is a set of two or more equations that are solved together to find a common solution. To find the solution, you can use methods like substitution, elimination, or graphing. Finding triples (x,y,z) in a system of equations is important as it gives a unique solution and helps understand the relationship between the variables. A system of equations can have more than one solution, depending on whether the equations are dependent or independent. The best approach to solving a system of equations varies depending on the specific problem and the different methods available.
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Find all triples $(x,\,y,\,z)$ of real numbers that satisfy the system of equations

$x^3=3x-12y+50\\y^3=12y+3z-2\\z^3=27z+27x$
 
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Observe the following identities:
$x^3-3x-2=(x-2)(x+1)^2\\y^3-12y-16=(y-4)(y+2)^2\\z^3-27z-54=(z-6)(z+3)^3$

Suppose $x>2$, we then have

$-12y+50=x^3-3x>2\implies y<4$

$z^3-27z=27x>54 \implies z>6$

$y^3-12y=3z-2>16 \implies y>4$

which leads to a contradiction.

Now, assume $x<2$, we then have

$-12y+50=x^3-3x<2 \implies y>4$

$3z-2=y^3-12y>16 \implies z>6$

But this leads to

$27x=z^3-27z>54$ which is impossible.

THus, $x=2$ and that gives the only solution set $(x,\,y,\,z)=(2,\,4,\,6)$.
 

FAQ: System of Equations: Find Triples $(x,y,z)$

How do I solve a system of equations to find triples (x,y,z)?

To solve a system of equations to find triples (x,y,z), you will need to use a method called substitution or elimination. First, choose one of the equations and solve it for one of the variables (x, y, or z). Then, substitute this value into the other equations and solve for another variable. Continue this process until you have solved for all three variables and have a set of ordered triples (x,y,z) that satisfy all of the equations.

Can I use a calculator to solve a system of equations to find triples (x,y,z)?

Yes, you can use a calculator to solve a system of equations to find triples (x,y,z). Many scientific and graphing calculators have built-in functions for solving systems of equations. However, it is important to understand the steps and concepts behind solving a system of equations, as relying solely on a calculator may not always be feasible.

How many solutions can a system of equations have when finding triples (x,y,z)?

A system of equations can have one, infinite, or no solutions when finding triples (x,y,z). If the equations are consistent and independent, there will be one unique solution. If the equations are consistent and dependent, there will be infinite solutions. If the equations are inconsistent, there will be no solutions.

What if I have more than three equations when finding triples (x,y,z)?

If you have more than three equations when finding triples (x,y,z), you will need to use a method called Gaussian elimination. This method involves using elementary row operations to reduce the system of equations to a simpler form, making it easier to solve. Once the system is in reduced row-echelon form, you can easily find the values of x, y, and z.

Can I use matrices to solve a system of equations to find triples (x,y,z)?

Yes, you can use matrices to solve a system of equations to find triples (x,y,z). Matrices can be used to represent a system of equations in a compact and organized form. By using elementary row operations on the matrix, you can solve the system and find the values of x, y, and z. This method is especially useful when dealing with larger systems of equations.

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