2 Equations/2 Unknown Study Guide

Back in your dim, dark days of algebra I, you learned that you can solve one equation with one unknown:


x + 5 = 6


x = 6 - 1


x = 5

You should also recall that it takes two equations to solve equations with 2 unknowns. There are two ways to solve those type of problems, let's review them now with the following equations:

Now we'll substitute y = -2 back into one of the equations to solve for x:

However, in physics we typically need to get one variable in terms of the other, and the substitute that back into the other equation. Let's review that now: