Use Taylor's theorem to show a function is differentiable at x=0

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SUMMARY

This discussion focuses on using Taylor's theorem to demonstrate the differentiability of the function f(x) = (1 - |x|^a)(e^x)^a at x = 0, under the condition that a > 1/2. The estimation of |(e^x) - x - 1| for 0 ≤ x ≤ 1 is derived from the Taylor series expansion, yielding the expression |(e^x) - x - 1| = (x^2)/2 + (x^3)/6 + (x^4)/24 + ... The analysis indicates that the remainder terms in the Taylor expansion are dominated by the x^2 term, which supports the conclusion of differentiability at x = 0.

PREREQUISITES
  • Taylor's theorem
  • Understanding of differentiability
  • Knowledge of limits and continuity
  • Basic calculus, specifically series expansions
NEXT STEPS
  • Study the application of Taylor's theorem in proving differentiability
  • Explore the concept of Lagrange remainder in Taylor series
  • Investigate the implications of differentiability in real analysis
  • Review the properties of exponential functions and their series expansions
USEFUL FOR

Students of calculus, mathematicians focusing on real analysis, and anyone interested in the application of Taylor's theorem in proving function properties.

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Homework Statement



Use Taylor's theorem to estimate |(ex)-x-1| for 0≤x≤1. Thus prove that if a>(1/2) then:

f(x)=(1-|x|a)*(ex)a is differentiable at x=0

Homework Equations





The Attempt at a Solution



So |(ex)-x-1|=(x^2)/2+(x^3)/6+(x^4)/24...

But I don't see how this helps, I have considered using the Lagrange remainder as well but again I can't see how that would help either. Any help would be greatly appreciated.
 
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Since the lowest power of x in that formula is 2 so, for x less than 1, it is less than x.
 

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