WEBVTT

1
00:00:00.000 --> 00:00:04.389
Here is the problem: 3x minus 7 equals 11.

2
00:00:04.839 --> 00:00:09.553
A linear equation in x: isolate x using inverse operations.

3
00:00:10.353 --> 00:00:11.793
Start with the equation.

4
00:00:12.243 --> 00:00:13.985
Add 7 to both sides.

5
00:00:14.435 --> 00:00:16.432
Divide both sides by 3.

6
00:00:17.232 --> 00:00:20.750
Now look at the graph of the left side minus the right side.

7
00:00:21.200 --> 00:00:24.973
It crosses zero exactly at the solutions we found.

8
00:00:25.773 --> 00:00:28.339
So the answer is x equals 6.

9
00:00:28.789 --> 00:00:37.996
Doing the same operation to both sides keeps the equation balanced. Undoing addition, then multiplication, leaves x alone.

10
00:00:38.796 --> 00:00:45.147
x equals 6: left side equals 11, right side equals 11, which checks out.