00:01
Okay, this question asks us to find the slope of the tangent to the curve at x equals 1 .842.
00:06
So we need the derivative for this.
00:09
Looks like we'll be doing a quotient rule here, so we'll set ourselves up a nice big quotient.
00:16
Okay, quotient rule is going to be denominator times derivative of numerator.
00:21
Derivative numerator, negative e to the negative x, that negative popping down in front, minus numerator times the derivative of the denominator.
00:35
Of 1 is 0, the derivative of ln4x will just be 1 over.
00:42
This is all over the denominator square.
00:47
Okay, we could spend time simplifying this, but really we just need to substitute in our x value at this point.
00:54
We've got 1 plus ln 4 times 1 .824, sorry.
01:05
Okay, times negative, e to the negative 1 .842, minus.
01:10
E to the negative 1 .842, there's one over 1 .842, all divided by 1 plus ln 4 times 1 .842, all squared.
01:31
Okay, and go to the calculator for this.
01:33
I'm sure you a little trick to save us typing this 1 .842 a bunch of times.
01:38
Okay, i'm going to type this number in first, hit enter.
01:41
It's now stored in the calculator's short -term memory, and i can access it with this...