Why Does arctan Ensure Continuity in Sequences?

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SUMMARY

The discussion centers on the continuity of the arctangent function and its implications for sequences. It establishes that if \( f \) is a continuous function, then the convergence of a sequence \( (x_n) \) to \( x \) implies that \( f(x_n) \) converges to \( f(x) \). Specifically, it highlights that while the converse is not universally true, it holds for the arctangent function, as demonstrated by the relationship \( \text{arctan}(u_n) \to \text{arctan}(u) \) leading to \( x_n \to x \). This continuity property is leveraged to show that \( f \) as tangent results in the desired convergence.

PREREQUISITES
  • Understanding of continuity in mathematical functions
  • Familiarity with sequences and limits in calculus
  • Knowledge of the arctangent function and its properties
  • Basic understanding of the tangent function and its continuity
NEXT STEPS
  • Study the properties of continuous functions in calculus
  • Explore the implications of the Intermediate Value Theorem
  • Learn about the convergence of sequences and series
  • Investigate the behavior of inverse trigonometric functions
USEFUL FOR

Mathematicians, calculus students, and educators seeking to deepen their understanding of continuity in functions and its effects on sequences.

Ted123
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If [itex]f[/itex] is continuous function and [itex](x_n)[/itex] is a sequence then [tex]x_n \to x \implies f(x_n) \to f(x)[/tex]
The converse [tex]f(x_n) \to f(x) \implies x_n \to x[/tex] in general isn't true but why is it true, for example, if [itex]f[/itex] is arctan?
 
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Let [itex]\mbox{arctan}(u_n) \to \arctan(u)[/itex]. Write [itex]x_n = \mbox{arctan}(u_n)[/itex] and [itex]x = \mbox{arctan}(u)[/itex], so [itex]x_n \to x[/itex]. Now using [itex]x_n \to x \implies f(x_n) \to f(x)[/itex], with [itex]f[/itex] as tan gives the result. Why can you do this?
 

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