Using Chain Rule to Find du/dT & du/dv: Step-by-Step Guide

In summary, the conversation discusses the use of the chain rule to find the derivative of a function with respect to multiple variables. The chain rule states that the derivative is equal to the partial derivative with respect to one variable multiplied by the derivative of that variable with respect to the independent variable, plus the partial derivative with respect to the other variable multiplied by the derivative of that variable with respect to the independent variable. The conversation also explains the difference between the symbols "∂" and "d" in multivariable calculus.
  • #1
sphyics
102
0
If a function is given by u = u(T,v) how to use the chain rule to write how u changes with respect to T & v.
Please specify the steps involved.
i understand chain rule as [itex]\frac{du}{dx}[/itex] = [itex]\frac{du}{dy}[/itex] [itex]\frac{dy}{dx}[/itex]
 
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  • #2
Assuming T and v are both functions of x, the chain rule gives:
du/dx = (∂u/∂T)(dT/dx) + (∂u/∂v)(dv/dx)
 
  • #3
mathman said:
Assuming T and v are both functions of x, the chain rule gives:
du/dx = (∂u/∂T)(dT/dx) + (∂u/∂v)(dv/dx)
very much thanks for ur quick response :)

how does the symbol differs in meaning with d
 
  • #4
[itex] \partial [/itex] (read "partial") is basically the equivalent of [itex] d [/itex] in multivariable calculus, it means you take the derivative of a function with respect to a variable while considering all other variables as constants during that operation.

For example if I have
[tex] F = x^2 + 2xy + \frac{x}{y} [/tex]
Then
[tex] \frac{\partial F}{\partial x} = 2x + 2y + \frac{1}{y} [/tex]
Can you find [itex] \frac{\partial F}{\partial y} [/itex]? :)
 
  • #5
JHamm said:
[itex]
Can you find [itex] \frac{\partial F}{\partial y} [/itex]? :)

= 2x - x/y2

i think that's the right answer :)
 
  • #6
I think so too :)
 
  • #7
Appreciate ur help :)
 

1. What is the chain rule?

The chain rule is a mathematical rule that is used to find the derivative of a composite function. It states that the derivative of a composite function is equal to the derivative of the outer function multiplied by the derivative of the inner function. This rule is commonly used in calculus to find the derivatives of more complex functions.

2. How do I use the chain rule to find du/dT and du/dv?

To use the chain rule to find du/dT and du/dv, you first need to identify the outer function and the inner function. Then, you can use the formula d(u(v))/dv = du/dv * dv/dT to find the derivatives. Make sure to substitute in the appropriate values for each derivative.

3. Can you provide an example of using the chain rule to find du/dT and du/dv?

Sure, let's say we have the function u(v) = (3v + 4)^2. The outer function is (3v + 4)^2 and the inner function is 3v + 4. To find du/dT, we would use the formula du/dT = du/dv * dv/dT. In this case, du/dv = 2(3v + 4) and dv/dT = 3. Therefore, du/dT = 6(3v + 4) * 3 = 18(3v + 4).

4. When should I use the chain rule to find derivatives?

You should use the chain rule when you have a composite function, meaning a function within a function. This could include functions with exponents, logarithms, or trigonometric functions. The chain rule allows you to find the derivative of the entire function by breaking it down into smaller, more manageable parts.

5. Are there any common mistakes when using the chain rule?

Yes, there are a few common mistakes that can occur when using the chain rule. These include not identifying the outer and inner functions correctly, forgetting to use the chain rule formula, and not substituting in the correct values for each derivative. It's important to carefully follow the steps and double check your work to avoid these mistakes.

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