Integrating x and xdx: What's the Difference?

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SUMMARY

This discussion clarifies the necessity of specifying the variable of integration when performing integrals in calculus. It emphasizes that an integral must always include a differential, such as "dx" or "dy", to indicate the variable with respect to which the function is being integrated. The example provided, integrating the function Y=2x, illustrates that both ∫ 2x dx and ∫ y dx yield the same result, while ∫ y dy represents a different operation. Understanding these distinctions is crucial for accurate integration.

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  • Basic understanding of calculus concepts, particularly integration.
  • Familiarity with the notation of integrals, including differentials like "dx" and "dy".
  • Knowledge of functions and their representations, such as linear functions.
  • Ability to manipulate algebraic expressions for integration purposes.
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  • Study the Fundamental Theorem of Calculus to understand the relationship between differentiation and integration.
  • Learn about definite and indefinite integrals, including their applications in real-world scenarios.
  • Explore integration techniques such as substitution and integration by parts.
  • Practice solving integrals involving various functions to reinforce understanding of integration with respect to different variables.
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Make
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Hello. I'm sort of confused about when you can integrate... Say for example if you have dx you're sort of integrating a "hidden" constant, right? So you increase the power by one and either use the upper and lower limit or just add c: x+c. And similarly if you have xdx, again you increase the power by one and divide:0.5x^2, right? But when are you allowed to integrate? Namely, must you always first obtain dx or dvariable somehow? How do I obtain this in the following case for example: Y=2x? If it is not necessary, then what difference is there in integrating x or xdx? THANK YOU SO MUCH FOR YOUR HELP!
 
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Hi Make! :smile:

I'm not sure what you're asking, but does this help? …

When you integrate a function f(x), you have to say what you're integrating it with respect to.

Usually, obviously, it's with respect to x, in which case we write either

"integral of f(x) with respect to x"

or

"∫ f(x) dx".

You can't write an ∫ without a d(something).​

As to your y = 2x example, you can write ∫ 2x dx, or ∫ y dx … they're the same (but they're not the same as ∫ y dy, because that's integrating with respect to something different).
 
dead on answer for makes level of understanding :)
 

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