Math Problem Statement

The function [g] is defined over the real numbers. This table gives a few values of [g].

[x][3.9][3.99][3.999][4.001][4.01][4.1]

[g(x)]

[11.21]

[11.92]

[11.99]

[12.01]

[12.08]

[12.81]

What is a reasonable estimate for [\displaystyle \lim_{x\to 4}g(x)]?

Choose 1 answer:

Solution

We are given values of the function g(x)g(x) for several values of xx that are close to 4 from both the left and the right. Our goal is to estimate limx4g(x)\lim_{x \to 4} g(x) based on this data.

Approach:

The function's values near x=4x = 4 are:

  • As xx approaches 4 from the left:

    • g(3.9)=11.21g(3.9) = 11.21
    • g(3.99)=11.92g(3.99) = 11.92
    • g(3.999)=11.99g(3.999) = 11.99
  • As xx approaches 4 from the right:

    • g(4.001)=12.01g(4.001) = 12.01
    • g(4.01)=12.08g(4.01) = 12.08
    • g(4.1)=12.81g(4.1) = 12.81

Looking at the values near x=4x = 4, as x4x \to 4^-, g(x)g(x) approaches 11.99, and as x4+x \to 4^+, g(x)g(x) approaches 12.01. Since these values are very close to each other, it is reasonable to estimate that:

limx4g(x)=12\lim_{x \to 4} g(x) = 12

Answer:

The most reasonable estimate for limx4g(x)\displaystyle \lim_{x\to 4}g(x) is 12.


Would you like more details or have any questions? Here are five related questions to expand on this topic:

  1. What happens if the function values from the left and right are not close to each other?
  2. How would you use this technique if you had fewer data points around x=4x = 4?
  3. What is the formal definition of a limit and how does it apply to this problem?
  4. Can limits exist if the function is discontinuous at a point?
  5. How do we estimate limits when dealing with functions that oscillate as xx approaches a value?

Tip: When estimating limits from a table of values, check how close the function values are as xx approaches the target point from both sides!

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Math Problem Analysis

Mathematical Concepts

Limits
Functions
Continuous Functions

Formulas

Limit: lim_{x→c} f(x)

Theorems

Limit Theorem
Squeeze Theorem (conceptually, for estimating limits)

Suitable Grade Level

Grades 10-12