Math Problem Statement

On considère la fonction g définie sur I = [1, +∞[ par: g(x) = 2 - √(x^2 - 1).

Solution

Let's analyze the exercise in the image and go through each part in detail. Here is a breakdown of the problem:

We have a function gg defined on the interval I=[1,+[I = [1, +\infty[ with: g(x)=2x21.g(x) = 2 - \sqrt{x^2 - 1}.

The tasks are as follows:

1. Calculate limx+g(x)\lim_{x \to +\infty} g(x).

For this, we need to evaluate the behavior of g(x)g(x) as xx approaches infinity.

2. Show that the function gg is continuous on II.

To do this, we will need to verify that g(x)g(x) is defined and continuous on the interval [1,+[[1, +\infty[, focusing on any potential points of discontinuity.

3. Calculate limx1+g(x)g(1)x1\lim_{x \to 1^+} \frac{g(x) - g(1)}{x - 1} and interpret the result geometrically.

This expression is essentially the definition of the derivative of gg at x=1x = 1. Calculating this limit will give insight into the behavior of g(x)g(x) near x=1x = 1.

4. Show that x]1,+[\forall x \in ]1, +\infty[, g(x)=xx21g'(x) = \frac{-x}{\sqrt{x^2 - 1}}. Deduce the monotonicity of gg on II.

This requires differentiating g(x)g(x) and analyzing the sign of g(x)g'(x) to determine if g(x)g(x) is increasing or decreasing over II.

5. Draw the variation table of gg.

Using the results from the derivative and monotonicity, create a table that shows the behavior of g(x)g(x) over II.

6. Show that gg admits an inverse function g1g^{-1} defined on an interval JJ to be determined.

Here, we need to verify if gg is bijective (one-to-one) on II, allowing for the existence of an inverse function on a specific interval JJ.

7. Determine g1(y)g^{-1}(y) for all yJy \in J.

Finally, we’ll find an explicit expression for the inverse function g1(y)g^{-1}(y) on the interval JJ.


Would you like me to go through each part step-by-step with detailed solutions, or do you have specific questions about one of the tasks?

Relative Questions

  1. How do we calculate limits involving square roots as x+x \to +\infty?
  2. What conditions must be met to prove a function is continuous on an interval?
  3. How do we interpret the limit of a difference quotient geometrically?
  4. What are the criteria for determining if a function is monotonic?
  5. What steps are involved in finding an inverse function and determining its domain?

Tip

When calculating limits with square roots, consider rationalizing by multiplying the numerator and denominator by the conjugate, if needed, to simplify the expression.

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Math Problem Analysis

Mathematical Concepts

Limits
Continuity
Derivatives
Monotonicity
Inverse Functions

Formulas

Limit as x approaches infinity
Definition of continuity on an interval
Difference quotient for derivative calculation
Derivative of functions involving square roots
Monotonicity and variation table

Theorems

Continuity of functions on an interval
Monotonicity theorem for derivatives
Inverse function theorem

Suitable Grade Level

University Level (Calculus I and II)