Math Problem Statement

Evaluate the limit: lim(x → ∞) [(2x^4 - 1 + 3x^2)/x] / [x√x - 4]

Solution

I see that you've uploaded an image containing a mathematical expression. Let me extract the equation and solve it.

The given expression appears to be:

limx2x41+3x2xxx4.\lim_{x \to \infty} \frac{\frac{2x^4 - 1 + 3x^2}{x}}{x\sqrt{x} - 4}.

Let me solve this step by step.


Step 1: Simplify the numerator

The numerator is:

2x41+3x2x.\frac{2x^4 - 1 + 3x^2}{x}.

Divide each term by xx:

2x4x1x+3x2x=2x31x+3x.\frac{2x^4}{x} - \frac{1}{x} + \frac{3x^2}{x} = 2x^3 - \frac{1}{x} + 3x.

Thus, the numerator becomes 2x3+3x1x2x^3 + 3x - \frac{1}{x}.


Step 2: Write the denominator

The denominator is:

xx4.x\sqrt{x} - 4.


Step 3: Combine the numerator and denominator

The overall expression becomes:

limx2x3+3x1xxx4.\lim_{x \to \infty} \frac{2x^3 + 3x - \frac{1}{x}}{x\sqrt{x} - 4}.


Step 4: Analyze dominant terms as xx \to \infty

  • In the numerator, the dominant term is 2x32x^3 since x3x^3 grows faster than xx or 1x-\frac{1}{x}.
  • In the denominator, the dominant term is xx=x3/2x\sqrt{x} = x^{3/2}, as it grows much faster than 4-4.

So, the expression simplifies to:

limx2x3xx.\lim_{x \to \infty} \frac{2x^3}{x\sqrt{x}}.


Step 5: Simplify the dominant terms

Simplify 2x3xx\frac{2x^3}{x\sqrt{x}}:

2x3xx=2x3x3/2=2x33/2=2x3/2.\frac{2x^3}{x\sqrt{x}} = \frac{2x^3}{x^{3/2}} = 2x^{3 - 3/2} = 2x^{3/2}.


Step 6: Evaluate the limit

As xx \to \infty, 2x3/22x^{3/2} \to \infty. Therefore, the limit diverges to infinity:

limx2x41+3x2xxx4=.\lim_{x \to \infty} \frac{\frac{2x^4 - 1 + 3x^2}{x}}{x\sqrt{x} - 4} = \infty.


Final Answer:

\boxed{\infty}


Do you want a breakdown of any step or further clarifications?


Related Questions:

  1. How do we determine the dominant term in a rational expression as xx \to \infty?
  2. Why is x3/2x^{3/2} the dominant term in the denominator?
  3. Can limits like these approach finite values instead of diverging?
  4. How does L'Hopital's Rule apply in cases of infinity/infinity indeterminate forms?
  5. How does dividing by the highest power of xx simplify such limits?

Tip:

Always identify and focus on the dominant terms for large values of xx to simplify expressions and evaluate limits efficiently.

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Math Problem Analysis

Mathematical Concepts

Limits
Asymptotic Analysis
Simplification of Rational Expressions

Formulas

lim(x → ∞) f(x)/g(x) for dominant terms

Theorems

Concept of Dominant Terms in Limits

Suitable Grade Level

Undergraduate Mathematics or Advanced High School Calculus