WEBVTT

1
00:00:00.000 --> 00:00:04.563
Here is the problem: negative 9x minus 2 equals negative 2.

2
00:00:05.013 --> 00:00:09.611
A linear equation in x: isolate x using inverse operations.

3
00:00:10.411 --> 00:00:11.874
Start with the equation.

4
00:00:12.324 --> 00:00:14.158
Add 2 to both sides.

5
00:00:14.608 --> 00:00:17.069
Divide both sides by negative 9.

6
00:00:17.869 --> 00:00:21.433
Now look at the graph of the left side minus the right side.

7
00:00:21.883 --> 00:00:25.668
It crosses zero exactly at the solutions we found.

8
00:00:26.468 --> 00:00:28.709
So the answer is x equals 0.

9
00:00:29.159 --> 00:00:38.447
Doing the same operation to both sides keeps the equation balanced. Undoing addition, then multiplication, leaves x alone.

10
00:00:39.247 --> 00:00:46.364
x equals 0: left side equals negative 2, right side equals negative 2, which checks out.