Find derivative where f(x) has three products

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In summary, the conversation is discussing how to find the maximum and minimum values of a function, specifically F(x) = x^(2/3)(x^2 - 4). The suggested method is to use the product rule, but it is also possible to simplify the equation by multiplying through with x^2/3. The final answer is (8(x+1)(x-1)) / (3x^(1/3)). The conversation also mentions checking the domain and ensuring that the expression exists at the maximum and minimum values.
  • #1
cloudboy
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Homework Statement



Trying to find all Max and Min.

F(x) = x^(2/3)(x^2 - 4)

Homework Equations


I know to use the product rule

The Attempt at a Solution



I tried and got this answer:

x^(10/3) + (2(x+2)(x-2)) / 3x^(1/3)
 
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  • #2
You could also just multiple the x^2/3 through so that you don't have to bother with the product rule.
 
  • #3
Thanks a lot! I got (8(x+1)(x-1)) / (3x^(1/3)) which is the right answer.
 
  • #4
Using the product rule gives
[itex]\frac{2}{3}[/itex]x[itex]^{-1/3}[/itex]*(x[itex]^{2}[/itex]-4) + 2*x[itex]^{5/3}[/itex]

modifying this gives (try it):
x[itex]^{-1/3}[/itex]*([itex]\frac{8}{3}[/itex]x[itex]^{2}[/itex] - [itex]\frac{8}{3}[/itex])

For min/max equal both factors of this equation to 0 and off course check the domain. Does the expression exist at min/max?
 

1. What is a derivative?

A derivative is a mathematical concept that measures the instantaneous rate of change of a function with respect to its independent variable. In other words, it tells us how much a function is changing at a specific point.

2. How do you find the derivative of a function with three products?

To find the derivative of a function with three products, you can use the product rule, which states that the derivative of two functions multiplied together is equal to the first function times the derivative of the second function plus the second function times the derivative of the first function. This rule can be applied multiple times for functions with more than two products.

3. Can you give an example of finding the derivative of a function with three products?

Sure. Let's say we have the function f(x) = x^2 * sin(x) * ln(x). To find the derivative, we would use the product rule, starting with the first two products: (x^2)' * sin(x) + x^2 * (sin(x))'. The derivative of x^2 is 2x, and the derivative of sin(x) is cos(x), so our equation becomes 2x * sin(x) + x^2 * cos(x). We then apply the product rule again for the remaining two products, giving us a final derivative of 2x * sin(x) * ln(x) + x^2 * cos(x) * ln(x) + x^2 * sin(x)/x.

4. Are there any other rules or methods for finding derivatives of functions with multiple products?

Yes, there are several other rules and methods, such as the quotient rule, chain rule, and power rule. These rules can be used in combination with the product rule to find the derivative of a function with multiple products. It is important to understand and practice these rules in order to accurately find derivatives of more complex functions.

5. Why is finding derivatives of functions with multiple products important?

Finding derivatives of functions with multiple products is important because it allows us to analyze and understand the behavior of these functions. Derivatives can tell us about the rate of change, extrema, and concavity of a function, which are all important concepts in various areas of science, engineering, and economics. They are also necessary for solving optimization problems and solving differential equations, making them a fundamental tool in many scientific fields.

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