Math Problem Statement

Given that lim x→0 f (x) = 2 and lim x→0 g(x) = 0, solve the following limits using limit laws that can be solved, or explain why it cannot be solved. Remember to only use one law at a time and justify any laws that require justifications. lim x→0 f (x)3 − g(x) 4 √g(x) − 16

lim x→0 f (x)3 − g(x) 4 √g(x) − 16

Solution

The problem involves solving the following limit:

limx0f(x)3g(x)g(x)16\lim_{x \to 0} \frac{f(x)^3 - g(x)}{\sqrt{g(x)} - 16}

Given that:

limx0f(x)=2andlimx0g(x)=0\lim_{x \to 0} f(x) = 2 \quad \text{and} \quad \lim_{x \to 0} g(x) = 0

Let us break down the limit step by step.

Step 1: Substitution of limits at x=0x = 0

First, substitute x=0x = 0 into the expression to see what it yields.

  • From the given, limx0f(x)=2\lim_{x \to 0} f(x) = 2, so f(0)=2f(0) = 2.
  • From the given, limx0g(x)=0\lim_{x \to 0} g(x) = 0, so g(0)=0g(0) = 0.

Substitute f(x)=2f(x) = 2 and g(x)=0g(x) = 0 into the expression:

f(x)3g(x)g(x)16230016=80016=816=12\frac{f(x)^3 - g(x)}{\sqrt{g(x)} - 16} \Rightarrow \frac{2^3 - 0}{\sqrt{0} - 16} = \frac{8 - 0}{0 - 16} = \frac{8}{-16} = -\frac{1}{2}

Step 2: Check for indeterminate form

The substitution leads to the following result:

816=12\frac{8}{-16} = -\frac{1}{2}

So, we have a finite value, and no indeterminate form like 00\frac{0}{0} arises. This means we do not need to apply any advanced limit laws such as L'Hôpital's Rule.

Step 3: Conclusion

The limit evaluates directly as:

limx0f(x)3g(x)g(x)16=12\lim_{x \to 0} \frac{f(x)^3 - g(x)}{\sqrt{g(x)} - 16} = -\frac{1}{2}

Further Questions:

  1. How does L'Hôpital's Rule apply to limits that result in indeterminate forms like 00\frac{0}{0}?
  2. What happens if f(x)f(x) and g(x)g(x) had different limiting values at x=0x = 0?
  3. What are the general rules for applying limits to rational functions?
  4. How can we interpret the behavior of functions at a point if both limits lead to the same value?
  5. What is the significance of continuous functions in evaluating limits?

Tip:

Always check for indeterminate forms first. If an indeterminate form like 00\frac{0}{0} or \frac{\infty}{\infty} arises, then more advanced tools like L'Hôpital's Rule or algebraic simplification are often needed.

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Limits
Continuity
Substitution in Limits
Limit Laws

Formulas

lim (x → a) [f(x)^3 - g(x)] / [√g(x) - 16]

Theorems

Limit Substitution
Continuity Theorem

Suitable Grade Level

Grades 11-12