Math Problem Statement

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La f(x) være en funksjon som er kontinuerlig for x ∈ [a, b], to ganger deriverbar for x ∈ (a, b), og der f(a) = f'(a) = f(b). Vis at det da finnes en c ∈ (a, b) slik at f''(c) = 0. Finn et eksempel på en funksjon f(x) og et tilhørende intervall (a, b) slik at resultatet over holder.

Solution

The problem you've uploaded involves a continuous function f(x)f(x) and asks to show the existence of a point c(a,b)c \in (a, b) such that f(c)=0f''(c) = 0. It also asks to find an example of a function f(x)f(x) and an interval (a,b)(a, b) such that this result holds.

Let's break down the problem:

  1. Given Information:

    • The function f(x)f(x) is continuous on the closed interval [a,b][a, b] and twice differentiable on the open interval (a,b)(a, b).
    • f(a)=f(a)=f(b)f(a) = f'(a) = f(b).
  2. Part 1: Show the existence of a point c(a,b)c \in (a, b) such that f(c)=0f''(c) = 0.

    • This is a classic application of Rolle's Theorem, which states that if a function is continuous on a closed interval [a,b][a, b], differentiable on the open interval (a,b)(a, b), and if f(a)=f(b)f(a) = f(b), then there exists at least one point c(a,b)c \in (a, b) where f(c)=0f'(c) = 0.
    • Here, you're also given that f(a)=f(b)f'(a) = f(b), so you apply Rolle's Theorem again to the first derivative f(x)f'(x), implying that there exists a point c(a,b)c \in (a, b) where f(c)=0f''(c) = 0.
  3. Part 2: Find an example of a function f(x)f(x) and a corresponding interval [a,b][a, b] such that the result holds.

    • An example of such a function could be f(x)=x33x+2f(x) = x^3 - 3x + 2. You would then find an interval [a,b][a, b] for which the given conditions apply, and verify that f(c)=0f''(c) = 0 at some point in that interval.

Let me know if you would like to proceed with solving this or need more clarification.

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Math Problem Analysis

Mathematical Concepts

Calculus
Continuity
Differentiability

Formulas

Rolle's Theorem
Second derivative test

Theorems

Rolle's Theorem

Suitable Grade Level

Grades 11-12