Math Problem Statement

Use limx→cf(x)=3 and limx→cg(x)=−2 to find the limit. Write the exact answer. Do not round.

limx→c([f(x)−5]2g(x)⎯⎯⎯⎯⎯⎯√3)

Solution

We are asked to find the limit:

limxc([f(x)5]2g(x)3)\lim_{x \to c} \left( \sqrt{ \frac{[f(x) - 5]^2}{g(x)^3}} \right)

Given:

  • limxcf(x)=3\lim_{x \to c} f(x) = 3
  • limxcg(x)=2\lim_{x \to c} g(x) = -2

Step-by-step Solution:

  1. Break down the limit: The limit expression can be broken down into smaller parts: [ \lim_{x \to c} \left( \sqrt{ \frac{[f(x) - 5]^2}{g(x)^3}} \right) = \sqrt{ \lim_{x \to c} \left( \frac{[f(x) - 5]^2}{g(x)^3} \right) } ] Since square roots and limits commute when the inside is non-negative, we can take the limit inside the square root.

  2. Evaluate the numerator: [ \lim_{x \to c} [f(x) - 5]^2 = [ \lim_{x \to c} (f(x) - 5) ]^2 = [ 3 - 5 ]^2 = (-2)^2 = 4 ]

  3. Evaluate the denominator: limxcg(x)3=(limxcg(x))3=(2)3=8\lim_{x \to c} g(x)^3 = \left( \lim_{x \to c} g(x) \right)^3 = (-2)^3 = -8

  4. Combine the results: Now, combine the numerator and denominator: limxc[f(x)5]2g(x)3=48=12\lim_{x \to c} \frac{[f(x) - 5]^2}{g(x)^3} = \frac{4}{-8} = -\frac{1}{2}

  5. Apply the square root: Finally, apply the square root to the result: 12\sqrt{-\frac{1}{2}} However, this is not a real number. The square root of a negative number is imaginary. Thus, we can express the result as: i12\boxed{i \frac{1}{\sqrt{2}}} where ii is the imaginary unit.

Exact answer: i12i \frac{1}{\sqrt{2}}


Would you like more details or have any questions?

Here are 5 follow-up questions to consider:

  1. How do limits behave when involving complex numbers?
  2. What are the properties of limits involving square roots?
  3. How does the limit of a function change if g(x)g(x) were positive instead of negative?
  4. Why is the square root of a negative number expressed using ii?
  5. What happens to limits when both numerator and denominator approach zero?

Tip: Always check whether the limit produces a real or complex result when dealing with square roots of negative numbers.

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Math Problem Analysis

Mathematical Concepts

Limits
Square Roots
Imaginary Numbers

Formulas

lim(x→c) f(x) = L
lim(x→c) sqrt(f(x)) = sqrt(lim(x→c) f(x))
lim(x→c) [f(x) - 5]^2 = (lim(x→c) (f(x) - 5))^2

Theorems

Limit Laws
Properties of Square Roots
Complex Numbers (Imaginary Unit i)

Suitable Grade Level

College-level Calculus or Advanced High School Mathematics