WEBVTT

1
00:00:00.000 --> 00:00:04.609
Here is the problem: 9a squared minus 16b squared.

2
00:00:05.059 --> 00:00:07.230
Factor a two-variable polynomial.

3
00:00:08.030 --> 00:00:10.364
Write the polynomial in standard form.

4
00:00:10.814 --> 00:00:24.583
Factor the homogeneous part. The remaining factor is homogeneous of degree 2, so set b equals 1, factor the one-variable polynomial 9a squared minus 16, then restore b so every term has degree 2.

5
00:00:25.033 --> 00:00:26.484
Write the factorization.

6
00:00:27.284 --> 00:00:31.731
So the answer is (3a minus 4b)(3a plus 4b).

7
00:00:32.181 --> 00:00:39.344
9a squared minus 16b squared equals (3a minus 4b)(3a plus 4b).

8
00:00:40.144 --> 00:00:48.050
Expanding (3a minus 4b)(3a plus 4b) gives back 9a squared minus 16b squared.