Another differentiation question

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Homework Statement



Supposed "f" is a differentiable function. Write the expression for the derivative of the following function.

a) h(x) = -4x^3 * f(x)

b) h(x) = 2/\sqrt{x}* f(x)

Homework Equations



N/a

The Attempt at a Solution



Would the answers just be (using the product rule)

a) h'(x) = -4x^3 * f '(x) + f(x) * -12x^2

and

b) h'(x) = 2/\sqrt{x} * f '(x) + f(x) * -x^-2


Sort of seems to simple... Thanks again
 
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a) Yes, b) \frac{2}{\sqrt{x}} is not \frac{-1}{x^2}
 
Last edited:
There are two things I don't understand about this problem. First, when finding the nth root of a number, there should in theory be n solutions. However, the formula produces n+1 roots. Here is how. The first root is simply ##\left(r\right)^{\left(\frac{1}{n}\right)}##. Then you multiply this first root by n additional expressions given by the formula, as you go through k=0,1,...n-1. So you end up with n+1 roots, which cannot be correct. Let me illustrate what I mean. For this...

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