Describe why the graphing method is not always the best method to solve a system of equations.

Question

Not understanding why it wouldn't work solve a system of equations.

Answer 1

Hi Phyllis;

I have never been presented with this question before.  I will take a guess.

 

Some equations are three-dimensional, x, y and z.  The graphing method is typically presented in two dimensions, x and y.

Answer 2

I agree with Vivian, but I would like to add that, even in two dimensions, the solution may not have integer or even rational coordinates.  All you can get from the graphing method is a rough approximation of the solution.

Answer 3

Phyllis:

 

As Vivian points out, graphing is ONLY useful in 2-dimensions (2D).  A computer application (Matlab or other), can plot things in 3D for visual analysis, but manual plotting only makes sense in 2D.  Why?  Because you are plotting on a 2D surface.  Perhaps that is the thrust of the question.  Plotting 3 equations with 3 unknowns (or higher) is NEVER attempted in practice.  It makes no sense whatsoever.  Plotting in 4D for four equations with 4 unknowns is even tougher (Let me know if you can do it ;-)

 

The only time this question even makes sense is for two equations with two unknowns.  Graphing two equations is VITAL to understanding, but after mastering the techniques, plotting becomes relatively unimportant and cumbersome.