00:01
We're given the function f of x equals x minus 4 over x squared minus 16.
00:05
We want to know why it has a removable discontinuity at x equals 4.
00:10
To do that, i'm going to show you.
00:11
We're going to take that denominator and factor it into the difference of two squares.
00:16
And when i do so, we're going to eliminate this factor here of x minus 4.
00:21
That is going to be where your hole appears, because once that's removed, it looks like you're going to have a value.
00:30
Answer at x equals 4, but we're not.
00:33
This is going to create a hole in our graph.
00:37
So now we're going to say the f of 4 and the limit of x equals 4 exists, but they are not equal.
00:44
And that is true, because at f of 4, the function f of x is going to be undefined.
00:52
So the limit of as f of x equals 4 does not exist.
00:56
It does.
00:57
F of 4 is undefined...