Integral of a function of various variables

In summary, when taking the integral of a function z with respect to t, the assumption is made that both x and y are functions of t alone. Without knowing more about x(t) and y(t), the expression for f cannot be simplified.
  • #1
Jhenrique
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When I have a function z = f(x, y), i. e., a function of various variables, the differential form of z is: [tex]dz = \frac{\partial f}{\partial x} dx + \frac{\partial f}{\partial y} dy[/tex] or the derivative of z is: [tex]\frac{dz}{dt} = \frac{\partial f}{\partial x} \frac{dx}{dt} + \frac{\partial f}{\partial y} \frac{dy}{dt}[/tex] So, analogously, if I take the integral of z wrt t, so how come to be the expression for f?
 
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  • #2
Jhenrique said:
When I have a function z = f(x, y), i. e., a function of various variables, the differential form of z is: [tex]dz = \frac{\partial f}{\partial x} dx + \frac{\partial f}{\partial y} dy[/tex] or the derivative of z is: [tex]\frac{dz}{dt} = \frac{\partial f}{\partial x} \frac{dx}{dt} + \frac{\partial f}{\partial y} \frac{dy}{dt}[/tex] So, analogously, if I take the integral of z wrt t, so how come to be the expression for f?
When you take the derivative of z with respect to t, you are tacitly assuming that both x and y are functions of t alone. That is, that x = x(t) and y = y(t).

With that assumption, ##\int f(x, y) dt = \int f(x(t), y(t)dt##. As far as I know, that can't be simplified without knowing more about x(t) and y(t).
 

Related to Integral of a function of various variables

What is the definition of an integral of a function of various variables?

The integral of a function of multiple variables is a mathematical concept that represents the area under the curve of the function in a given region of the coordinate plane. It is a way to calculate the "total" value of a function over a certain area or volume.

How is the integral of a function of various variables calculated?

The integral of a function of multiple variables is typically calculated using a process called integration, which involves breaking down the region of interest into smaller pieces and approximating the area under the curve using these smaller pieces. This process can be done analytically using mathematical formulas or numerically using approximation techniques.

What is the difference between a single variable integral and a multiple variable integral?

In a single variable integral, the function being integrated and the region of integration are both one-dimensional. In a multiple variable integral, the function and/or the region may have two or more dimensions, making the calculation more complex.

What are the applications of integrals of functions of various variables?

Integrals of functions of multiple variables have numerous applications in math and science, including finding the volumes of 3D shapes, calculating probabilities in statistics, and determining the center of mass of an object. They are also used in physics, engineering, and economics to model and analyze real-world phenomena.

Are there any special techniques for solving integrals of functions of various variables?

Yes, there are various techniques for solving integrals of functions of multiple variables, including substitution, integration by parts, and using special formulas such as the Gaussian integral. These techniques can help simplify the integral and make it easier to solve.

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