Math Problem Statement

𝑓(π‘₯) = sqrt(2π‘₯2 + 5π‘₯ + 2)

Solution

The given function is:

f(x)=2x2+5x+2f(x) = \sqrt{2x^2 + 5x + 2}

Let’s break down a few key concepts about this function.


1. Domain of the Function

Since f(x)f(x) contains a square root, the expression inside the square root 2x2+5x+22x^2 + 5x + 2 must be non-negative:

2x2+5x+2β‰₯02x^2 + 5x + 2 \geq 0

To determine the domain, we solve the quadratic inequality.

  1. Find the roots:
    Use the quadratic formula x=βˆ’bΒ±b2βˆ’4ac2ax = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}, where a=2a = 2, b=5b = 5, and c=2c = 2.

    = \frac{-5 \pm \sqrt{9}}{4} = \frac{-5 \pm 3}{4}$$ So the roots are: $$x = -\frac{1}{2}, \quad x = -2$$
  2. Solve the inequality 2x2+5x+2β‰₯02x^2 + 5x + 2 \geq 0:
    We need to determine the sign of the quadratic expression in the intervals formed by these roots:

    • (βˆ’βˆž,βˆ’2)(-\infty, -2)
    • (βˆ’2,βˆ’12)(-2, -\frac{1}{2})
    • (βˆ’12,∞)(-\frac{1}{2}, \infty)

    For a quadratic of the form ax2+bx+cax^2 + bx + c, if a>0a > 0, the expression is positive outside the roots. Therefore, the solution to the inequality is:

    (βˆ’βˆž,βˆ’2]βˆͺ[βˆ’12,∞)(-\infty, -2] \cup \left[-\frac{1}{2}, \infty\right)

    Domain:
    The domain of the function is: (βˆ’βˆž,βˆ’2]βˆͺ[βˆ’12,∞)(-\infty, -2] \cup \left[-\frac{1}{2}, \infty\right)


2. Range of the Function

The function involves a square root, so the range will be non-negative, i.e., f(x)β‰₯0f(x) \geq 0. The minimum value of the square root occurs when the expression inside is minimized. This is tricky because it depends on 2x2+5x+22x^2 + 5x + 2, which is non-negative across the domain.

Therefore, the range is:

[0,∞)[0, \infty)


3. Derivative (Slope of the Function)

To find the rate of change or slope of the function, we need the derivative using the chain rule.

fβ€²(x)=122x2+5x+2β‹…ddx(2x2+5x+2)f'(x) = \frac{1}{2\sqrt{2x^2 + 5x + 2}} \cdot \frac{d}{dx}(2x^2 + 5x + 2)

fβ€²(x)=122x2+5x+2β‹…(4x+5)f'(x) = \frac{1}{2\sqrt{2x^2 + 5x + 2}} \cdot (4x + 5)

Thus, the derivative is:

fβ€²(x)=4x+522x2+5x+2f'(x) = \frac{4x + 5}{2\sqrt{2x^2 + 5x + 2}}


4. Behavior of the Function (Increasing/Decreasing)

  • The function is increasing when fβ€²(x)>0f'(x) > 0.
  • This happens when 4x+5>04x + 5 > 0, i.e., x>βˆ’54x > -\frac{5}{4}.
  • The function is decreasing when x<βˆ’54x < -\frac{5}{4}.

5. Asymptotic Behavior

There are no vertical asymptotes since the function is defined in terms of a square root polynomial. Also, as xβ†’βˆžx \to \infty or xβ†’βˆ’βˆžx \to -\infty, the function will grow without bound, meaning:

lim⁑xβ†’Β±βˆžf(x)=∞\lim_{x \to \pm \infty} f(x) = \infty


Would you like more details or have any questions?


Related Questions

  1. How do you solve quadratic inequalities step by step?
  2. What are the rules for applying the chain rule in differentiation?
  3. How do we determine where a function is increasing or decreasing?
  4. How do we find the range of complex functions involving square roots?
  5. What is the meaning of asymptotic behavior for polynomial-root functions?

Tip: When solving quadratic inequalities, always test values within each interval to confirm the sign.

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Math Problem Analysis

Mathematical Concepts

Algebra
Quadratic Inequalities
Square Root Functions
Differentiation

Formulas

Quadratic formula: x = (-b Β± sqrt(b^2 - 4ac)) / 2a
Derivative: f'(x) = (4x + 5) / (2sqrt(2x^2 + 5x + 2))

Theorems

Quadratic Inequality Theorem
Chain Rule in Differentiation

Suitable Grade Level

Grades 10-12