Math Problem Statement

solve these limits

lim->\infty ,(4x+2)/(|x|+6x)

lim->-\infty ,(4x+2)/(|x|+6x)

Solution

We need to evaluate the following limits:

limx4x+2x+6x\lim_{x \to \infty} \frac{4x+2}{|x|+6x}

limx4x+2x+6x\lim_{x \to -\infty} \frac{4x+2}{|x|+6x}

Step 1: Consider xx \to \infty

For xx \to \infty, we know that x=x|x| = x, so the given function simplifies to:

4x+2x+6x=4x+27x\frac{4x+2}{x+6x} = \frac{4x+2}{7x}

Now, divide both numerator and denominator by xx:

4+2x7\frac{4 + \frac{2}{x}}{7}

As xx \to \infty, the term 2x0\frac{2}{x} \to 0, so we get:

47\frac{4}{7}

Step 2: Consider xx \to -\infty

For xx \to -\infty, we know that x=x|x| = -x, so the function becomes:

4x+2x+6x=4x+25x\frac{4x+2}{-x+6x} = \frac{4x+2}{5x}

Dividing both numerator and denominator by xx:

4+2x5\frac{4 + \frac{2}{x}}{5}

As xx \to -\infty, the term 2x0\frac{2}{x} \to 0, so we get:

45\frac{4}{5}

Final Answers:

limx4x+2x+6x=47\lim_{x \to \infty} \frac{4x+2}{|x|+6x} = \frac{4}{7}

limx4x+2x+6x=45\lim_{x \to -\infty} \frac{4x+2}{|x|+6x} = \frac{4}{5}


Would you like a detailed explanation of any step?

Related Questions:

  1. What happens if x|x| is replaced by a different function, such as x2x^2?
  2. How do we handle limits involving absolute values in more complex expressions?
  3. What if we had a function of the form (ax+b)/(x+cx)(ax+b)/(|x|+cx)? How does the limit depend on aa and cc?
  4. How would the result change if we considered one-sided limits instead?
  5. How does the presence of higher-degree terms in the numerator or denominator affect the limit?

Tip:

When solving limits involving absolute values, always consider separate cases for x>0x > 0 and x<0x < 0 to avoid incorrect simplifications.

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Limits
Absolute Value
Rational Functions

Formulas

lim (x → ∞) f(x) = L
lim (x → -∞) f(x) = L
Division by the highest degree term in a rational function

Theorems

Limit properties
Behavior of absolute value in limits

Suitable Grade Level

Grades 11-12