Math Problem Statement

Nilai limit lim (x -> ∞) dari (√(9x^2 - 6x + 2) - (3x - 5)) adalah ....

Solution

The limit in the image can be written as:

limx(9x26x+2(3x5))\lim_{x \to \infty} \left( \sqrt{9x^2 - 6x + 2} - (3x - 5) \right)

We can simplify this step by step.

Step 1: Simplify the square root term

We begin by focusing on the square root expression 9x26x+2\sqrt{9x^2 - 6x + 2}. As xx approaches infinity, the term 9x29x^2 dominates because it grows much faster than the linear term 6x-6x or the constant 22.

Thus, for large xx, we approximate the expression inside the square root as: 9x26x+29x2=3x\sqrt{9x^2 - 6x + 2} \approx \sqrt{9x^2} = 3x

However, this approximation isn't exact, so we'll handle it rigorously by factoring x2x^2 from the terms inside the square root: 9x26x+2=x96x+2x2\sqrt{9x^2 - 6x + 2} = x\sqrt{9 - \frac{6}{x} + \frac{2}{x^2}}

As xx \to \infty, the fractions involving xx become very small, so: 96x+2x29=3\sqrt{9 - \frac{6}{x} + \frac{2}{x^2}} \to \sqrt{9} = 3

Thus, for large xx: 9x26x+2x3=3x\sqrt{9x^2 - 6x + 2} \approx x \cdot 3 = 3x

Step 2: Subtract the second term

Now subtract the second term from the expression: 3x(3x5)=3x3x+5=53x - (3x - 5) = 3x - 3x + 5 = 5

Step 3: Take the limit

Since the difference simplifies to 55 as xx approaches infinity, we conclude: limx(9x26x+2(3x5))=5\lim_{x \to \infty} \left( \sqrt{9x^2 - 6x + 2} - (3x - 5) \right) = 5

Thus, the value of the limit is 5.

Let me know if you want more details, or have any questions!

Here are some related questions to practice:

  1. What is the limit of limx(x2+x+1x)\lim_{x \to \infty} (\sqrt{x^2 + x + 1} - x)?
  2. How does the square root function behave as xx \to \infty?
  3. What would change in the solution if the expression under the square root had a higher-degree term?
  4. How can L'Hôpital's Rule be used to find limits involving indeterminate forms?
  5. What is the limit limx(4x2x2x)\lim_{x \to \infty} (\sqrt{4x^2 - x} - 2x)?

Tip: Always remember to simplify complex expressions by focusing on dominant terms for large values of xx.

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Math Problem Analysis

Mathematical Concepts

Limits
Algebraic Simplification
Square Roots
Asymptotic Behavior

Formulas

lim (x -> ∞) (√(ax^2 + bx + c) - (dx + e))
Factoring and simplifying expressions for large x

Theorems

Limit Theorem for Rational and Irrational Functions
Asymptotic Approximation

Suitable Grade Level

Grades 11-12