00:01
All right, we're looking at a walkthrough for question 25 out of the 3 .9 exercises.
00:05
Now, this section of questions are a little bit interesting because they're actually asking us for an equation of a line, a tangent line specifically.
00:15
So what you remember about derivatives is that a derivative will find you the slope equation at a very specific point.
00:25
But now i want to create a tangent line.
00:28
So i'm going to need to know what the slope of that tangent line is and then throw it into an equation as well.
00:35
So for these questions, i'm actually going to have to do two things.
00:40
So for the first one, i'm going to have to find the value of the point and then i'm going to actually have to find the slope at that point.
00:53
And then once i have that information, i can actually throw it in and calculate it from there.
01:01
So for the very first one here for 25, they want us to use the function f of x is equal to 6 the power of x, and they want us to find the tangent line when my value for x is 2.
01:16
So really i'm trying to solve what is the value of the function when f is 2.
01:23
And the value of that function for f is 2 is 6 squared and 6 squared happens to be 36.
01:30
So i have this point now that is at 2 and 36.
01:37
Now to find the slope of a tangent line at that point, i'm looking at the derivative.
01:44
So for this, i need to find the derivative of that function.
01:49
So to do that, i'm going to have to use my rules for when i have a power with a variable exponent.
02:00
So with that i keep my power the same, so a to the power of x, and then i'd have my natural log of my base.
02:10
So when i look at something like this question, 6 to the power of x would say the same, but then i'd multiply that by natural log of 6.
02:22
So that finds me the slope formula...