Math Problem Statement

We now have

lim x → ∞ (4x − ln(x)) = lim x → ∞ 4x 1 −

ln(x)

4x

.

Let's first focus on

lim x → ∞

ln(x)

4x

.

Since

ln(x) →

as

x → ∞,

then this limit is indeterminate of type

.

Using l'Hospital's rule, we find the following.

lim x → ∞

ln(x)

4x

= lim x → ∞

1

=

Solution

To evaluate the limit

limxln(x)4x,\lim_{x \to \infty} \frac{\ln(x)}{4x},

we notice that as xx approaches infinity, both ln(x)\ln(x) and 4x4x approach infinity, resulting in an indeterminate form of type \frac{\infty}{\infty}. We can apply L'Hôpital's rule, which states that for limits of the form \frac{\infty}{\infty}, we can take the derivative of the numerator and the denominator.

Taking the derivatives:

  1. The derivative of the numerator, ln(x)\ln(x), is 1x\frac{1}{x}.
  2. The derivative of the denominator, 4x4x, is 44.

Now, applying L'Hôpital's rule:

limxln(x)4x=limx1x4=limx14x.\lim_{x \to \infty} \frac{\ln(x)}{4x} = \lim_{x \to \infty} \frac{\frac{1}{x}}{4} = \lim_{x \to \infty} \frac{1}{4x}.

As xx approaches infinity, 14x\frac{1}{4x} approaches 00:

limxln(x)4x=0.\lim_{x \to \infty} \frac{\ln(x)}{4x} = 0.

Substituting back into the original limit we are evaluating:

limx(4xln(x))=limx4xlimxln(x)=0=.\lim_{x \to \infty} (4x - \ln(x)) = \lim_{x \to \infty} 4x - \lim_{x \to \infty} \ln(x) = \infty - 0 = \infty.

Thus, the overall limit is:

limx(4xln(x))=.\lim_{x \to \infty} (4x - \ln(x)) = \infty.

Summary:

  1. The limit limxln(x)4x=0\lim_{x \to \infty} \frac{\ln(x)}{4x} = 0.
  2. Therefore, limx(4xln(x))=\lim_{x \to \infty} (4x - \ln(x)) = \infty.

Would you like more details on any part of this process, or do you have other questions? Here are some related questions you might find interesting:

  1. What are some other examples where L'Hôpital's rule can be applied?
  2. How does the growth rate of logarithmic functions compare to polynomial functions?
  3. Can you provide examples of limits that result in forms other than \frac{\infty}{\infty}?
  4. What happens to the limit if we change the coefficients in 4x4x to a larger number?
  5. How does the concept of limits apply in real-world scenarios?

Tip: When dealing with limits approaching infinity, always check if the form is indeterminate, as this often indicates the use of L'Hôpital's rule or algebraic manipulation.

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Math Problem Analysis

Mathematical Concepts

Limits
L'Hôpital's Rule
Logarithmic Functions

Formulas

lim x → ∞ (ln(x) / 4x)
L'Hôpital's Rule

Theorems

L'Hôpital's Rule

Suitable Grade Level

Grades 11-12