00:01
This question is systems of linear equations and substitution and elimination.
00:07
For this question, we want to solve this linear system of equations.
00:13
So first, let's call the equations 1, 2, and 3.
00:21
And often when we have more than 2 equations, it's easier to use elimination than substitution.
00:28
So let's use elimination.
00:32
Notice that there are 2 ys in this equation and 2 y in this equation and they have opposite signs so it's really easy just to eliminate y by adding two to three we add the left sides and the right sides to get this which we can simplify by dividing by two now let's eliminate y in another way so one way to do this is to add double of equation one to equation two and this gives us the exact same equation as we got before.
01:29
So we can't eliminate another variable, x or z, even if we eliminated y in another way, we would also get this equation.
01:42
And so all we can do now is treat z as a free variable...