Partial Derivatives: Show bz(x)=az(y)

In summary, the conversation discusses how to show that bz(x) = az(y) for the function z=f(ax+by), where a and b are constants. The participants suggest using the chain rule and letting u = ax + by to keep f general.
  • #1
Lonely Lemon
22
0

Homework Statement



Suppose that z=f(ax+by), where a and b are constants. Show that bz(x) = az(y).

z(x) means partial derivative of z with respect to x, as for z(y).

Homework Equations





The Attempt at a Solution



Say z=ax+by

z(x) = a

z(y) = b

So bz(x) = ba = ab = az(y)

I'm not sure that this is a correct analysis - because I know f(ax+by) doesn't necessarily mean z = ax+by... How should I interpret this problem?
 
Physics news on Phys.org
  • #2
Keep f general and use the chain rule. It might help to let u = ax + by.
 

Related to Partial Derivatives: Show bz(x)=az(y)

1. What is a partial derivative?

A partial derivative is a type of derivative that measures the rate of change of a function with respect to one of its variables, while holding all other variables constant. It is useful in multi-variable calculus, where functions have more than one independent variable.

2. What is the notation for partial derivatives?

The notation for partial derivatives is similar to that of regular derivatives, but with a subscript denoting which variable is being held constant. For example, the partial derivative of a function f(x,y) with respect to x is written as ∂f/∂x, and the partial derivative with respect to y is written as ∂f/∂y.

3. How do you find the partial derivative of a function?

To find the partial derivative of a function, you take the derivative of the function with respect to the variable in question, treating all other variables as constants. This can be done using the standard rules of differentiation, such as the power rule and the product rule.

4. How does the chain rule apply to partial derivatives?

The chain rule also applies to partial derivatives. This means that when a function is composed of multiple sub-functions, the partial derivative of the composite function can be found by taking the partial derivatives of each sub-function and multiplying them together.

5. What is the specific example of bz(x)=az(y) and how do you show it using partial derivatives?

The given equation, bz(x)=az(y), represents a function that is dependent on two variables, x and y. To show this using partial derivatives, we can take the partial derivative of bz(x) with respect to x, which would be b, and the partial derivative of bz(x) with respect to y, which would be 0. Similarly, taking the partial derivative of az(y) with respect to x would result in 0, and the partial derivative with respect to y would be a. Therefore, the two sides of the equation are equal, showing that bz(x) and az(y) are both partial derivatives of the same function.

Similar threads

  • Calculus and Beyond Homework Help
Replies
3
Views
2K
  • Calculus and Beyond Homework Help
Replies
8
Views
570
  • Calculus and Beyond Homework Help
Replies
6
Views
637
  • Calculus and Beyond Homework Help
Replies
2
Views
572
Replies
9
Views
806
  • Calculus and Beyond Homework Help
Replies
6
Views
840
  • Calculus and Beyond Homework Help
Replies
2
Views
692
  • Calculus and Beyond Homework Help
Replies
1
Views
702
  • Calculus and Beyond Homework Help
Replies
5
Views
2K
  • Calculus and Beyond Homework Help
Replies
4
Views
618
Back
Top