Question

Systems of equations can be solved by graphing or by using substitution or elimination. What are the pros and cons of each method? Which method do you like best? Why? What circumstances would cause you to use a different method?

Answer 1

Graphing:

Pro: gives you a visual picture of what's going on and is good for really big numbers

Con: if your graphing skills are not accurate or the solution is not at the intersection of a grid line, you have to estimate your answer.

Substitution:

Pro: Gives you an exact answer

Con: Sloppy calculations can cause incorrect answers and if one equation is not already solved for a variable (y = or x = ), you have to do extra work

Elimination

Pro: Works for any system of linear equations. After one or two steps you have a one-step equation to solve and you have half of your solution.

Con: Sloppy calculations can lead to incorrect solutions

If I need a rough idea of the solution, I graph. If one of the equations is already solved for y or for x, I use substitution. If neither of the above is true, I use elimination.

I always use elimination since I can describe the procedure algorithmically and therefore have a calculator/computer do it for me. :-P