Understanding d and Δ in Integration

In summary, "d" and "delta" are both used in calculus, but they have different meanings. "Delta" represents a change in a variable, while "d" represents an infinitesimal change. When integrating, "d" is typically used for the variable being integrated with respect to, while "delta" is used for the limits of integration. In the case of partial derivatives, "d" is used to represent a small change in one variable while holding the other variables constant.
  • #1
cheez
26
0
How come d becomes (delta)? after integration? I thought d and delta is the same thing. What's the difference between them?

For example,
dA = - PdV

After intergration, it becomes
(delta)A = -(integral)PdV

I can't type the symbols.

thx!
 
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  • #2
If the integration is going say, from x0 to x1, then (delta)A is an abbreviation for A(x1)-A(x0). (integral)dA=A but applying the limits I get (delta)A. Not at all the same thing as the dA symbol.
 
  • #3
Delta just means "change in" and is used for just plain change or average change, nothing instantaneous or infintesimal. With calculus, most of the deltas turn into d's, but not all as shown here
 
  • #4
I am having the same problem, if I take the entropy for example

We have (delta - the triangle)S=q/t
then we have dS=dq/T
and then there's partial derivatives

what is the difference between them?

If I integrate say the partial derivative of dq = q? or would that equal (delta)q?

Thank you
 
  • #5


Thank you for your question. In mathematics and science, "d" and "Δ" both represent change or difference, but they have different meanings and contexts. In integration, "d" represents an infinitesimal change, while "Δ" represents a finite change.

In the example you provided, "dA" represents an infinitesimal change in area, while "ΔA" represents a finite change in area. When we integrate, we are finding the cumulative effect of infinitesimal changes, which is why "d" becomes "Δ" after integration.

In summary, "d" and "Δ" may seem similar, but they have different meanings in integration and represent different types of changes. I hope this helps clarify the difference between them.
 

1. What is the difference between d and Δ in integration?

D and Δ are both used in integration, but they represent different concepts. D represents the derivative, which is the rate of change of a function at a specific point. Δ represents the change in a variable, and is often used in the context of finding the area under a curve.

2. How do d and Δ relate to each other in integration?

In integration, d and Δ are related through the Fundamental Theorem of Calculus. This theorem states that the derivative (d) and the integral (Δ) are inverse operations of each other, meaning that they "undo" each other. This allows us to solve for either d or Δ by using the other.

3. When should I use d and when should I use Δ in integration?

D is typically used when finding the instantaneous rate of change of a function at a specific point. Δ is used when finding the total change in a variable over a range of values. In integration, we use d to find the derivative of a function and Δ to find the area under a curve.

4. How do I calculate d and Δ in integration?

To calculate d, we use the rules of differentiation to find the derivative of a function. To calculate Δ, we use the rules of integration, such as the power rule or substitution, to find the area under a curve. It is important to note that finding the exact values of d and Δ may require advanced mathematical techniques depending on the complexity of the function.

5. What are some real-world applications of understanding d and Δ in integration?

Understanding d and Δ in integration is essential in many fields of science and engineering. For example, in physics, we can use integration to calculate the displacement, velocity, and acceleration of a moving object. In economics, integration is used to calculate total revenue and profit. In chemistry, it is used to determine the amount of reactants and products in a chemical reaction. Essentially, any time we need to find the total change or rate of change of a variable, integration (using d and Δ) is a useful tool.

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