Is the Limit of a Continuous Function Equal to the Limit of its Variable?

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If a function f is continuous in a neighborhood around x = a, then the limit of f as x approaches a is equal to f evaluated at a. This is expressed mathematically as lim(x → a) f(x) = f(lim(x → a) x), which simplifies to lim(x → a) f(x) = f(a). The continuity of f at x = a ensures that both sides of the equation are equal. This relationship reinforces the concept of continuity in mathematical analysis. Thus, the limit of a continuous function at a point is indeed equal to the function's value at that point.
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If f is continuous in some neighborhood of x = a, then is the following true:

\lim_{x \rightarrow a} f(x) = f( \lim_{x \rightarrow a} x)?
 
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If f is continuous in some neighborhood of x = a, it is also continuous at x = a, because x = a is contained in the neighborhood. The l.h.s equals the r.h.s because of the fact that the limit as x tends to 'a' of f(x) equals 'f(a)' (because of continuity of f) and on the other hand, f of the limit of x as 'x tends to a' is obviously f(a) since lim(x) = a as x --> a
 
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JG89 said:
If f is continuous in some neighborhood of x = a, then is the following true:

\lim_{x \rightarrow a} f(x) = f( \lim_{x \rightarrow a} x)?

This an anorthodoxe way of writting : f is continuous at x=a <====>
\lim_{x \rightarrow a} f(x)=f(a)

But i suppose is correct since \lim_{x\rightarrow a}x = a
 
JG89 said:
If f is continuous in some neighborhood of x = a, then is the following true:

\lim_{x \rightarrow a} f(x) = f( \lim_{x \rightarrow a} x)?

That is true. This makes clear the idea of continuity.
 
Insights auto threads is broken atm, so I'm manually creating these for new Insight articles. In Dirac’s Principles of Quantum Mechanics published in 1930 he introduced a “convenient notation” he referred to as a “delta function” which he treated as a continuum analog to the discrete Kronecker delta. The Kronecker delta is simply the indexed components of the identity operator in matrix algebra Source: https://www.physicsforums.com/insights/what-exactly-is-diracs-delta-function/ by...

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