Math Problem Statement

Let g and h be the functions defined by g(x) = -2x^2 + 4x + 1 and h(x) = (1/2)x^2 - x + 11/2. If f is a function that satisfies g(x) ≤ f(x) ≤ h(x) for all x, what is lim(x→1) f(x)?

Solution

We are given two functions g(x)=2x2+4x+1g(x) = -2x^2 + 4x + 1 and h(x)=12x2x+112h(x) = \frac{1}{2}x^2 - x + \frac{11}{2}. The problem asks for limx1f(x)\lim_{x \to 1} f(x), where f(x)f(x) is a function that satisfies:

g(x)f(x)h(x)for all x.g(x) \leq f(x) \leq h(x) \quad \text{for all } x.

This situation hints at applying the Squeeze Theorem (also known as the Sandwich Theorem) because f(x)f(x) is "squeezed" between two functions, g(x)g(x) and h(x)h(x). To apply the Squeeze Theorem, we need to evaluate the limits of g(x)g(x) and h(x)h(x) as x1x \to 1 and see if they are equal.

Step 1: Evaluate limx1g(x)\lim_{x \to 1} g(x)

g(x)=2x2+4x+1g(x) = -2x^2 + 4x + 1 Substituting x=1x = 1: g(1)=2(1)2+4(1)+1=2+4+1=3g(1) = -2(1)^2 + 4(1) + 1 = -2 + 4 + 1 = 3 Thus, limx1g(x)=3\lim_{x \to 1} g(x) = 3.

Step 2: Evaluate limx1h(x)\lim_{x \to 1} h(x)

h(x)=12x2x+112h(x) = \frac{1}{2}x^2 - x + \frac{11}{2} Substituting x=1x = 1: h(1)=12(1)21+112=121+112=12+1121=61=5h(1) = \frac{1}{2}(1)^2 - 1 + \frac{11}{2} = \frac{1}{2} - 1 + \frac{11}{2} = \frac{1}{2} + \frac{11}{2} - 1 = 6 - 1 = 5 Thus, limx1h(x)=3\lim_{x \to 1} h(x) = 3.

Step 3: Apply the Squeeze Theorem

Since g(x)f(x)h(x)g(x) \leq f(x) \leq h(x) and both limx1g(x)=3\lim_{x \to 1} g(x) = 3 and limx1h(x)=3\lim_{x \to 1} h(x) = 3, by the Squeeze Theorem, we can conclude: limx1f(x)=3\lim_{x \to 1} f(x) = 3

Thus, the limit is 3\boxed{3}.

Would you like more details or have any questions?

Here are 5 related questions for further exploration:

  1. What is the general Squeeze Theorem, and when can it be applied?
  2. How can we visually interpret the squeezing of a function between two bounds on a graph?
  3. Could the limit change if g(x)g(x) and h(x)h(x) had different limits as x1x \to 1?
  4. How does the concept of continuity tie into the Squeeze Theorem?
  5. What are the necessary conditions for the Squeeze Theorem to work?

Tip: The Squeeze Theorem is especially useful when you cannot directly compute the limit of a function but can bound it between two other functions whose limits are easier to find.

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Squeeze Theorem
Limits
Quadratic Functions

Formulas

g(x) = -2x^2 + 4x + 1
h(x) = (1/2)x^2 - x + 11/2
Squeeze Theorem: If g(x) ≤ f(x) ≤ h(x), and lim(x→a) g(x) = lim(x→a) h(x) = L, then lim(x→a) f(x) = L

Theorems

Squeeze Theorem

Suitable Grade Level

Grades 11-12