Asking about integral notation

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    Integral Notation
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Discussion Overview

The discussion revolves around the notation used in integral calculus, specifically questioning why the integral should be expressed as ##\int_{a}^{x} f(t)dt## instead of ##\int_{a}^{x} f(x)dx##. Participants explore the implications of variable naming in integrals and the potential for confusion that arises from using the same variable for different meanings.

Discussion Character

  • Conceptual clarification, Debate/contested

Main Points Raised

  • Some participants argue that using ##\int_{a}^{x} f(x)dx## is incorrect because it leads to confusion by using the same variable for different meanings, as the integral notation is typically defined with respect to a different variable, such as ##t##.
  • Others propose that the correct notation should be ##\int_{a}^{x} f(t)dt## to maintain clarity in the variable of integration.
  • A participant raises a parallel question regarding the incorrectness of writing $$\sum_{k = 1}^k a_k$$, suggesting a broader concern about variable usage in mathematical expressions.

Areas of Agreement / Disagreement

Participants express disagreement regarding the correct notation for integrals, with some supporting the use of ##t## and others questioning the implications of variable naming. The discussion remains unresolved as no consensus is reached on the preferred notation.

Contextual Notes

Participants highlight the importance of variable distinction in integrals, but the discussion does not resolve the underlying assumptions about notation conventions or the implications of variable choice.

songoku
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TL;DR
Why writing $$\int_{a}^{x} f(x) dx$$ is not correct?
Why should it be ##\int_{a}^{x} f(t)dt## ?

Couldn't it be like this:
Let F(x) = ##\int f(x)dx## so ##\int_{a}^{x} f(x)dx## = F(x) - F(a)

Thanks
 
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songoku said:
Summary: Why writing $$\int_{a}^{x} f(x) dx$$ is not correct?

Why should it be ##\int_{a}^{x} f(t)dt## ?

Couldn't it be like this:
Let F(x) = ##\int f(x)dx## so ##\int_{a}^{x} f(x)dx## = F(x) - F(a)

Thanks
The integral ##\displaystyle{\int_a^b f(t)\,dt}## is short for ##\displaystyle{\int_{t=a}^{t=b} f(t)\,dt}.## If you use the same letter (##b=t##) for two different meanings then you cause confusion.
 
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songoku said:
Summary: Why writing $$\int_{a}^{x} f(x) dx$$ is not correct?

Why should it be ##\int_{a}^{x} f(t)dt## ?

Couldn't it be like this:
Let F(x) = ##\int f(x)dx## so ##\int_{a}^{x} f(x)dx## = F(x) - F(a)

Thanks
Why is it not correct to write $$\sum_{k = 1}^k a_k$$
 
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Thank you very much for the explanation fresh_42 and PeroK
 

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