 In this video, we provide the solution to question number 12 for the practice final exam for math 12-10. We're given a function f of x equals the fourth root of x to the fourth plus 16, and we're asked to find the derivative. This one, we'll want to use the chain rule, where we see as an inner function x to the fourth plus 16, it's sitting inside of the outer function, the fourth root of x. So as we compute our derivative, we should recognize that f of x is equal to x to the fourth plus 16 raised to the one fourth power. And so then when we take the derivative using the chain rule, we'll force use the, on the outer derivative, the power rule. So we get one fourth times x to the fourth plus 16 raised to the negative three fourth power. Then we times it by the inner derivative, the derivative of x to the fourth plus 16, which is going to equal four x cubed. We see that these fours cancel out, and our derivative is going to look like x cubed over x to the fourth plus 16 raised to the three fourth power. Which we then would see that choice C is correct.