00:01
Proof at this limit is true using the epsilon delta proof.
00:04
So how this works is for every epsilon greater than zero.
00:10
So that's the input.
00:11
There needs to be a corresponding delta, the output, such that if zero is less than the absolute value of x minus, in this case free, because it's the limit as x approaches free, is less than delta.
00:32
Then the absolute value of the function, so 1 plus 1 fared x, minus the answer, so minus 2 is less than epsilon.
00:48
So let's start combining like terms, start on the right side.
00:53
So absolute value, so 1 minus 2, so negative 1, so 1 fair to x minus 1 is less than epsilon.
01:02
Now over here on the left, how can i make this look more like the one on the right? well, i can factor out a free.
01:13
Zero is less than three times the absolute value of one ferds x minus one is less than delta.
01:25
And now let's just divide everything by free.
01:28
0 is less than absolute value of 1 fared x minus 1 is less than delta over 3.
01:39
So now you should see at the middle parts are the same in both of them.
01:44
1 fared x minus 1 is less than epsilon and it's less than delta over 3.
01:52
So here we'll have our delta over 3 is equal to epsilon.
02:01
Now we want epsilon to be the input, so let's just multiply both sides by three.
02:08
So delta is equal to free epsilon.
02:13
And we now have, for every epsilon, that's the input, there is now a corresponding delta.
02:20
It's just three times as large.
02:23
And it needs to be positive.
02:25
Both epsilon and delta need to be positive.
02:29
And we have that...