00:02
Here we are asked to find the critical numbers for the function g of x equals 4x squared times 3d of x.
00:08
Now first we want to look at what the domain of this original function is, because critical numbers are values in the domain of the original function for which the first derivative is zero or undefined.
00:20
So we always want to be aware of the domain of the original function.
00:24
Will our work with our 4x squared times 3 to the x, any real number can be squared times 4.
00:32
The base of three to any real number.
00:36
So this domain is all reals.
00:42
So any values that i get for the derivative that's zero or undefined is in the domain of the original function.
00:49
And so i'm good with that.
00:51
So now next up, we're going to take our derivative.
00:54
So g prime of x.
00:57
This is a product.
00:58
So we have to use a product rule.
01:00
We have a number times a letter base to a number power.
01:03
That'll use the power rule, but then i have a number base to a letter power.
01:07
So that's a exponential function, and i need to use the derivative for exponential functions for that.
01:13
Now remember, differentiating a product, it's derivative of the first.
01:17
So derivative of 4x squared is 8x times the second factor, 3 to the x, plus the first 4x squared times the derivative of the second factor.
01:28
And the derivative of 3 to the x, the derivative of an exponential is the same exponential times the derivative of the exponent, the derivative of x is 1, and then if the base is not a, you also have to multiply by the natural log of the base...