Can you solve these 2 equations with 3 variables and prove the solutions?

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Homework Help Overview

The discussion revolves around solving a system of two equations with three variables, specifically focusing on the equations 3x + 2y + (1/3)z = 50 and x + y + z = 100. Participants explore the nature of the solutions, including whether they are unique or if multiple solutions exist, particularly under the constraint that the variables must be positive integers.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants discuss various methods for solving the equations, including substitution and row reduction techniques. There are questions about the uniqueness of solutions and the implications of assuming certain values for the variables. Some participants suggest exploring the conditions under which the solutions remain positive integers.

Discussion Status

The discussion is active, with participants providing insights into the nature of the solutions and the implications of different assumptions. There is recognition that the original poster's solution may not be the only one, and various interpretations of the problem are being explored. Some participants have offered guidance on methods to approach the problem, while others are seeking clarification on specific points.

Contextual Notes

There is an ongoing debate about whether the variables x, y, and z are constrained to be positive integers, which affects the nature of the solutions. Participants are also considering the implications of the equations in a real-world context, as the original poster is tasked with designing a problem based on these equations.

  • #31
They are not axis, they are vectors whose number turns out to be three. In that video the solution turns out to be a sum between a fixed vector and a linear combination of the vectors denoted by ##\vec a## and ##\vec b## (just for your information the last two vectors form the basis in the so-called null space of the coefficient matrix). In your problem the solution is a sum between a fixed vector ##(-150,250,0)^T## and a linear combination of a single vector ##(5/3,-8/3,1)^T## (the last vector is a basis for the null space of the coefficient matrix in your problem).
 
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  • #32
Hi @Nicola276:

I agree with Delta.
Delta² said:
Something tells me that the OP wanted to say that x,y,z are positive integers.
Equations seeking integer solutions are called Diophantine equations.

There is a discussion of these equations in

You may also find the following helpful. It is about a method for solving a single linear Diophantine equation.
Your problem involves two equations, but it is easy to transform it into one by eliminating one variable as shown by SammyS in post #28.

Regards,
Buzz
 
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