What is the partial derivative of f(x,y) with respect to x?

In summary, the partial derivative of the function f(x,y)=\sqrt[5]{x^7y^4} with respect to x is f_x(x,y)=\frac 7 5x^{\frac 2 5}y^{\frac 4 5}. This is found by using the power rule for derivatives and taking the derivative of each term separately. However, the denominator in the final answer should have an exponent of 5 instead of 4.
  • #1
rocomath
1,755
1
[SOLVED] Partial derivative ... check me please

[tex]f(x,y)=\sqrt[5]{x^7y^4}[/tex]

[tex]f_x(x,y)=\frac 1 5(x^7y^4)^{-\frac{4}{5}}(7x^6y^4)[/tex]

[tex]f_x(x,y)=\frac{7x^6y^4}{5\sqrt[5]{x^7y^4}}[/tex]

Correct?
 
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  • #2
rocomath said:
[tex]f(x,y)=\sqrt[5]{x^7y^4}[/tex]

[tex]f_x(x,y)=\frac 1 5(x^7y^4)^{-\frac{4}{5}}(7x^6y^4)[/tex]

[tex]f_x(x,y)=\frac{7x^6y^4}{5\sqrt[5]{x^7y^4}}[/tex]

Correct?
I don't think so.

HINT:

[tex]f(x,y) = x^{7/5}y^{4/5}[/tex]
 
  • #3
Hootenanny said:
I don't think so.

HINT:

[tex]f(x,y) = x^{7/5}y^{4/5}[/tex]
omg ... I'm embarassed :D

ok so ...

[tex]f_x(x,y)=\frac 7 5x^{\frac 2 5}y^{\frac 4 5}[/tex]
 
  • #4
rocomath said:
omg ... I'm embarassed :D

ok so ...

[tex]f_x(x,y)=\frac 7 5x^{\frac 2 5}y^{\frac 4 5}[/tex]
Sounds good to me :approve:
 
  • #5
Thanks Hootenanny :)
 
  • #6
rocomath said:
Thanks Hootenanny :)

A pleasure as always roco :smile:
 
  • #7
You would have gotten the same answer, but the denominator has the wrong exponent.
 

1. What is a partial derivative?

A partial derivative is a mathematical concept used to measure the rate of change of a multivariable function with respect to one of its variables, while holding all other variables constant.

2. Why are partial derivatives useful?

Partial derivatives are useful because they allow us to analyze how a function changes in response to changes in its variables. This can help us understand the behavior of complex systems and make predictions about their future states.

3. How do you calculate a partial derivative?

To calculate a partial derivative, you take the derivative of a function with respect to one of its variables, treating all other variables as constants. This can be done using standard differentiation rules and the chain rule.

4. What are some real-world applications of partial derivatives?

Partial derivatives are used in many fields, including physics, economics, and engineering. They can help us optimize processes, such as finding the maximum or minimum value of a function, and make predictions about complex systems.

5. Can you give an example of a partial derivative in action?

One example of a partial derivative in action is in economics, where it is used to measure the marginal rate of substitution, or how much of one good a person is willing to give up in order to obtain more of another good. This helps economists understand consumer behavior and make predictions about market trends.

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