Math Problem Statement

Does there exist a function f such that f(0) = −1,

f(2) = 6, and f ′(x) ≤ 2 for all x?

Solution

To determine whether such a function ff exists, let us analyze the problem step by step:

Problem Constraints:

  1. f(0)=1f(0) = -1
  2. f(2)=6f(2) = 6
  3. f(x)2f'(x) \leq 2 for all xx (the derivative condition restricts the slope of f(x)f(x)).

The key is to check whether the conditions on f(x)f'(x) allow the function ff to increase from 1-1 at x=0x = 0 to 66 at x=2x = 2, given that the maximum slope of the function is 2.

Step 1: Maximum possible increase

The derivative f(x)2f'(x) \leq 2 means that the rate of change of ff is at most 2. If ff increases at this maximum rate (constant slope of 2), then: f(x)=f(0)+2x.f(x) = f(0) + 2x. At x=2x = 2, the value of f(x)f(x) would be: f(2)=1+2(2)=3.f(2) = -1 + 2(2) = 3.

This is less than the required f(2)=6f(2) = 6. Therefore, no such function ff exists that satisfies all three conditions simultaneously.

Conclusion:

There does not exist a function ff such that f(0)=1f(0) = -1, f(2)=6f(2) = 6, and f(x)2f'(x) \leq 2 for all xx.

Would you like further explanation or additional examples? Here are some questions to deepen your understanding:

  1. Why does the derivative constraint restrict the maximum change of a function?
  2. What happens if the derivative condition f(x)2f'(x) \leq 2 is replaced by f(x)3f'(x) \leq 3?
  3. How does the Mean Value Theorem help us analyze such problems?
  4. Can we construct a piecewise function that "almost" satisfies the given conditions?
  5. How would the solution change if f(x)f'(x) could exceed 2 for some xx?

Tip: Use the Mean Value Theorem as a tool to link function values to derivative constraints in problems involving slope restrictions.

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Math Problem Analysis

Mathematical Concepts

Calculus
Derivative Constraints
Mean Value Theorem

Formulas

f(x) = f(a) + f'(c)(x-a) (from Mean Value Theorem)
Maximum possible change = max slope × interval length

Theorems

Mean Value Theorem

Suitable Grade Level

Grades 11-12 or Early College