00:01
In this problem we're given a function y or y is x to the 2rd multiplied by x plus 2 and we're asked to find the critical points and the external points of this function and since this function is a polynomial we know that the domain will be negative infinity to positive infinity so all the real numbers and once write this function as x to the 5 3rd plus 2 x to the 2 3rd so that we can take the derivative better.
00:31
Why do we need the derivative? because it needs out the derivative to 0, we can plan a big of course.
00:37
So let's first find the derivative.
00:39
Y prime then means no to be 5 third, x to the 2 third, plus 4 over 3, multiplied by 1, 4x with 1 3.
00:51
And this can be written as 1 3rd, x to the negative 1 3rd, multiplied by 5x plus 4.
01:00
Now let's set this to 0 to find a critical point.
01:04
First of all, we can see that when x is 0, this is undefined.
01:12
And x0 is actually isn't the domain, so this is one critical point.
01:17
Secondly, let's find the value of x that makes that y prime 0.
01:23
So 5x plus 4, 0, because we're trying to set this to 0...