Math Problem Statement

On considère la fonction f définie sur [1, 4/3] par f(x) = √((x-1)/4x). On désigne par (C) la courbe représentative de f dans un repère orthonormé (O, T, T'). Étudier la dérivabilité de f à droite en 1. Interpréter le résultat graphiquement. Dresser le tableau de variation de f. Tracer (C). Montrer que f réalise une bijection de [1, 4/3] sur [0, 1/4]. Montrer que pour tout x ∈ [0, 1/4], f⁻¹(x) = 1/(1 - 4x²). Tracer (C), la courbe de f⁻¹ dans le même repère. Montrer que pour tout x ∈ [0, 1/4], f⁻¹(x) = 1/(1 - 4x²). Déduire que ∫(0 to 1/4) f⁻¹(x) dx = ln(3/4). Calculer alors, en cm², l'aire de la partie du plan limitée par (C), l'axe des abscisses et les droites d'équations x = 1 et x = 4/3.

Solution

This is a mathematical problem set dealing with function analysis, differentiation, inverse functions, and integration. Here’s a breakdown of the key topics covered:

  1. Function Analysis and Differentiation:

    • Studying the differentiability of f(x)=x14xf(x) = \sqrt{\frac{x-1}{4x}} at x=1x = 1.
    • Creating a variation table.
    • Plotting the graph of f(x)f(x).
  2. Inverse Function Analysis:

    • Proving that ff is bijective from [1,43]\left[ 1, \frac{4}{3} \right] onto [0,14]\left[ 0, \frac{1}{4} \right].
    • Deriving the inverse function f1(x)f^{-1}(x).
    • Plotting the inverse function’s graph.
  3. Integral and Area Calculation:

    • Proving that f1(x)=114x2f^{-1}(x) = \frac{1}{1 - 4x^2} for x[0,14]x \in \left[ 0, \frac{1}{4} \right].
    • Evaluating the integral 01/4f1(x)dx\int_0^{1/4} f^{-1}(x)dx.
    • Using this to compute the bounded area.

Would you like detailed solutions for specific parts? Here are five related questions:

  1. How do you determine the differentiability of f(x)f(x) at a point?
  2. How do you establish that a function is bijective on a given interval?
  3. What steps are involved in finding the inverse of a function?
  4. How do you evaluate an integral involving a rational function?
  5. How do you compute an area under a curve using integration?

Tip: When proving bijectivity, always check both injectivity (one-to-one) and surjectivity (onto).

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Math Problem Analysis

Mathematical Concepts

Differentiation
Inverse Functions
Integration
Bijective Functions
Variation Tables

Formulas

f(x) = √((x-1)/(4x))
f⁻¹(x) = 1/(1 - 4x²)
∫(0 to 1/4) f⁻¹(x) dx = ln(3/4)

Theorems

Differentiability at a point
Bijectivity and inverse function properties
Integration of rational functions

Suitable Grade Level

Undergraduate level (Calculus, Analysis)