Certainty of being able to solve linear equation

  • Context: High School 
  • Thread starter Thread starter Mr Davis 97
  • Start date Start date
  • Tags Tags
    Linear Linear equation
Click For Summary

Discussion Overview

The discussion revolves around the nature of solutions for a specific linear equation involving two variables, ##a## and ##b##. Participants explore the implications of having one equation with two variables, questioning the common understanding that such systems are underdetermined and typically yield infinitely many solutions. The conversation delves into the uniqueness of solutions based on different interpretations and conditions applied to the variables.

Discussion Character

  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • Some participants assert that linear equations with two variables and one equation are underdetermined, leading to infinitely many solutions.
  • Others challenge this by suggesting that the specific equation presented may yield a unique solution when coefficients are compared.
  • A participant questions the notion of a "unique solution," arguing that the linear expression should allow for an infinite number of solutions due to the absence of discontinuities in its graph.
  • Another participant proposes that the perceived uniqueness might stem from restricting solutions to integers, leading to a specific solution under those conditions.
  • One participant provides a specific solution for ##a## in terms of ##b##, indicating that each value of ##b## yields a corresponding value of ##a##, thus supporting the idea of infinitely many solutions.
  • Another participant offers an example of a single equation in two variables to illustrate the concept of underdetermination.

Areas of Agreement / Disagreement

Participants express differing views on the nature of solutions for the equation, with no consensus reached on whether it leads to a unique solution or infinitely many solutions. The discussion remains unresolved regarding the implications of variable conditions on the solutions.

Contextual Notes

Participants reference various conditions (such as integer restrictions) that may affect the nature of the solutions, but these conditions are not universally accepted or agreed upon in the discussion.

Mr Davis 97
Messages
1,461
Reaction score
44
I have the linear equation ##a + (2a - b) \sqrt{2} = 4 + \sqrt{2}##. I commonly hear that for linear equations, if we have two variables and one equation, then the system is undertermined and there are infinitely many solutions. However, how does that jive with this example, where there is one unique solution after comparing coefficients?
 
Physics news on Phys.org
Mr Davis 97 said:
I have the linear equation ##a + (2a - b) \sqrt{2} = 4 + \sqrt{2}##. I commonly hear that for linear equations, if we have two variables and one equation, then the system is undertermined and there are infinitely many solutions. However, how does that jive with this example, where there is one unique solution after comparing coefficients?
I may be missing something here, but what "unique solution" are you referring to? This is a linear expression so it should have an infinite amount of solutions, as there are no discontinuites in its graph.
 
Mr Davis 97 said:
I have the linear equation ##a + (2a - b) \sqrt{2} = 4 + \sqrt{2}##. I commonly hear that for linear equations, if we have two variables and one equation, then the system is undertermined and there are infinitely many solutions. However, how does that jive with this example, where there is one unique solution after comparing coefficients?
It seems to me that you are restricting your solution to the integers. Solving your equation with respect to a gives a=\frac{(b+1)\sqrt{2} + 4}{1+2\sqrt{2}}, which gives one value of a for each value of b you insert in the formula.
 
Mr Davis 97 said:
I have the linear equation ##a + (2a - b) \sqrt{2} = 4 + \sqrt{2}##. I commonly hear that for linear equations, if we have two variables and one equation, then the system is undertermined and there are infinitely many solutions. However, how does that jive with this example, where there is one unique solution after comparing coefficients?
It depends on what type of equation you're working with.
If there are no conditions on a and b, then there are infinitely many solutions, one of which is ##a=\sqrt 2, b = 0##.
If a and b must be integers, then the coefficient of ##\sqrt 2## must be the same on both sides of the equation, which yields the unique solution a = 4 and b = 7.
 
  • Like
Likes   Reactions: Mr Davis 97
Mr Davis 97 said:
if we have two variables and one equation, then the system is undertermined and there are infinitely many solutions.

Consider the single equation in two variables: ##a + b = a + b + 1##
 

Similar threads

  • · Replies 19 ·
Replies
19
Views
4K
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 10 ·
Replies
10
Views
3K
  • · Replies 29 ·
Replies
29
Views
3K
  • · Replies 3 ·
Replies
3
Views
1K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 4 ·
Replies
4
Views
3K
  • · Replies 6 ·
Replies
6
Views
2K
  • · Replies 2 ·
Replies
2
Views
2K
Replies
2
Views
2K