Extended product rule for derivatives

In summary, the conversation discusses the product rule for differentiation and its extension for more than two terms. The formula for the extended product rule is (uvw)'=(uv)'w+(uv)w'=u'vw+uv'w+uvw'. It is suggested to consult a textbook or take notes more carefully in order to understand and apply this rule.
  • #1
musicfairy
101
0
Can someone please explain it to me? My handwriting wasn't at its best when I was taking notes in class and now I can't read it. The teacher showed an example that I jotted down but what's the general rule?
 
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  • #2
Maybe you should consult your textbook or take notes more carefully.
The usual product rule for differentiation reads
[tex]
(uv)'=uv'+u'v
[/tex]
where u,v are functions.

What do you mean by extended product rule?
 
  • #3
I meant if you have 3 or more terms, like y = sinxcosxlnx and you want the derivative.
 
  • #4
For three terms: (uvw)'=(uv)'w+(uv)w'=u'vw+uv'w+uvw'.

As you can see, this can be extended to 4 terms and beyond quite readily.
 
  • #5
It's easy to derive yourself, using the regular problem rule. If you have y = f(x)g(x)h(x), then use the formula Pete Callahan posted, using u=f(x), v=(g)h(x).
So then y' = uv' + vu'
Then use the product rule again to find v'
 
  • #6
Thanks everyone. This makes more sense now.
 

FAQ: Extended product rule for derivatives

What is the extended product rule for derivatives?

The extended product rule for derivatives is a mathematical rule used to find the derivative of a product of two or more functions. It is an extension of the basic product rule and is used when the product of functions is more complex.

How does the extended product rule differ from the basic product rule?

The extended product rule takes into account the product of more than two functions, while the basic product rule only applies to the product of two functions. It also involves taking the derivative of each individual function and then multiplying them together, rather than just applying a simple formula.

When should I use the extended product rule for derivatives?

The extended product rule should be used when the product of functions is more complex, such as when there are multiple functions being multiplied together or when one or more of the functions involves trigonometric, exponential, or logarithmic functions. It is also useful when the basic product rule cannot be applied directly.

Can you provide an example of how to use the extended product rule?

Sure, let's say we have the function f(x) = (x^2 + 3x)(2x^3 + 5). Using the extended product rule, we would first find the derivatives of each function: f'(x) = (2x + 3)(6x^2) + (x^2 + 3x)(6x) = 12x^3 + 18x^2 + 6x^3 + 18x = 18x^3 + 24x^2 + 18x. We then multiply these derivatives together to get the final derivative: f'(x) = (x^2 + 3x)(2x^3 + 5) = 18x^5 + 24x^4 + 18x^2 + 54x.

Are there any limitations or special cases for the extended product rule?

Yes, there are some limitations and special cases to keep in mind when using the extended product rule. For example, it cannot be applied to products of infinite series or when the functions are not continuous and differentiable. It also does not apply to products of vectors or matrices. Additionally, the order in which the functions are multiplied can affect the result, so it is important to carefully consider the order of operations when using this rule.

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