Math Problem Statement

suppose -2 <= f(x) <= x^2-4x+2 for all x = cannot equal 2 Which of the following MUST be true? Select all correct answer choices.

  1. lim x-> 2 f(x) = -2
  2. f(2) = -2
  3. lim x -> 0^- f(x) = lim x -> 0^+ f(x)
  4. lim x-> 0 f(x) does not exist

Solution

We are given that 2f(x)x24x+2-2 \leq f(x) \leq x^2 - 4x + 2 for all x2x \neq 2, and we need to determine which of the statements must be true. Let's analyze each option.

Option 1: limx2f(x)=2\lim_{x \to 2} f(x) = -2

  • We know that f(x)f(x) is bounded between 2-2 and x24x+2x^2 - 4x + 2, but no additional information about the behavior of f(x)f(x) as xx approaches 2 is given.
  • Without more details about the behavior of f(x)f(x) near x=2x = 2, this limit does not have to equal 2-2. The upper bound x24x+2x^2 - 4x + 2 evaluated at x=2x = 2 is also 2-2, but this alone is not sufficient to conclude the limit equals 2-2.

Thus, Option 1 is not necessarily true.

Option 2: f(2)=2f(2) = -2

  • The condition f(x)f(x) is defined for all x2x \neq 2, and we are not given the value of f(x)f(x) at x=2x = 2. Therefore, there is no information to confirm that f(2)=2f(2) = -2.

Thus, Option 2 is not necessarily true because we don't know if f(x)f(x) is even defined at x=2x = 2.

Option 3: limx0f(x)=limx0+f(x)\lim_{x \to 0^-} f(x) = \lim_{x \to 0^+} f(x)

  • The function f(x)f(x) is continuous for all x2x \neq 2, and there is no discontinuity mentioned at x=0x = 0.
  • Since f(x)f(x) is bounded by a continuous function x24x+2x^2 - 4x + 2, the left-hand limit (limx0f(x)\lim_{x \to 0^-} f(x)) and right-hand limit (limx0+f(x)\lim_{x \to 0^+} f(x)) must agree at x=0x = 0, as there is no indication of a discontinuity at this point.

Thus, Option 3 is true.

Option 4: limx0f(x)\lim_{x \to 0} f(x) does not exist

  • As discussed in Option 3, since f(x)f(x) is bounded by a continuous function and there is no indication of a discontinuity at x=0x = 0, the limit limx0f(x)\lim_{x \to 0} f(x) must exist.

Thus, Option 4 is false.

Conclusion:

The correct answer is:

  • Option 3: limx0f(x)=limx0+f(x)\lim_{x \to 0^-} f(x) = \lim_{x \to 0^+} f(x)

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Math Problem Analysis

Mathematical Concepts

Limits
Inequalities
Continuity

Formulas

lim_{x→c} f(x)
f(x) ≤ g(x) ≤ h(x) theorem (Squeeze Theorem)

Theorems

Squeeze Theorem
Continuity at a point

Suitable Grade Level

Grades 11-12