Math Problem Statement

f(x) = |x ^ 2 + x - 2| - 4

Solution

The function f(x)=x2+x24f(x) = |x^2 + x - 2| - 4 involves the absolute value of a quadratic function. Here's a step-by-step analysis of how to study this function:

Step 1: Analyze the quadratic inside the absolute value

The expression inside the absolute value is: x2+x2x^2 + x - 2 Factorize it: x2+x2=(x1)(x+2)x^2 + x - 2 = (x - 1)(x + 2)

Step 2: Determine where the quadratic changes sign

The roots of x2+x2x^2 + x - 2 are x=1x = 1 and x=2x = -2. These roots divide the number line into three intervals:

  • (,2)(-\infty, -2)
  • (2,1)(-2, 1)
  • (1,)(1, \infty)

Check the sign of x2+x2x^2 + x - 2 in each interval:

  • For x(,2)x \in (-\infty, -2): Both factors (x1)(x - 1) and (x+2)(x + 2) are negative, so the product is positive.
  • For x(2,1)x \in (-2, 1): The factor (x1)(x - 1) is negative, and (x+2)(x + 2) is positive, so the product is negative.
  • For x(1,)x \in (1, \infty): Both factors are positive, so the product is positive.

Thus:

\begin{cases} x^2 + x - 2, & \text{if } x \in (-\infty, -2) \cup (1, \infty), \\ -(x^2 + x - 2), & \text{if } x \in (-2, 1). \end{cases}$$ ### Step 3: Write $$f(x)$$ without the absolute value Using the analysis above: $$f(x) = \begin{cases} (x^2 + x - 2) - 4, & \text{if } x \in (-\infty, -2) \cup (1, \infty), \\ -(x^2 + x - 2) - 4, & \text{if } x \in (-2, 1). \end{cases}$$ Simplify each case: 1. For $$x \in (-\infty, -2) \cup (1, \infty)$$: $$f(x) = x^2 + x - 6$$ 2. For $$x \in (-2, 1)$$: $$f(x) = -x^2 - x - 2$$ ### Step 4: Analyze critical points and behavior 1. **Critical points**: The critical points occur where $$f'(x) = 0$$ or where $$f(x)$$ is not differentiable. - The derivative of $$f(x) = x^2 + x - 6$$ is $$f'(x) = 2x + 1$$. - The derivative of $$f(x) = -x^2 - x - 2$$ is $$f'(x) = -2x - 1$$. Check for non-differentiable points at $$x = -2$$ and $$x = 1$$ (where the absolute value changes): - At $$x = -2$$: $$f(x) = 6$$. - At $$x = 1$$: $$f(x) = -5$$. 2. **Domain**: $$f(x)$$ is defined for all real $$x$$. 3. **Range**: To determine the range, analyze the vertex of each quadratic piece. - For $$x \in (-\infty, -2) \cup (1, \infty)$$: The vertex of $$x^2 + x - 6$$ is at $$x = -\frac{1}{2}$$, and the parabola opens upwards. - For $$x \in (-2, 1)$$: The vertex of $$-x^2 - x - 2$$ is at $$x = -\frac{1}{2}$$, and the parabola opens downwards. ### Step 5: Graphical representation The function is piecewise quadratic, with a smooth transition at $$x = -2$$ and $$x = 1$$. The absolute value causes $$f(x)$$ to change behavior at these points. --- Would you like a detailed plot of this function or further numerical analysis? ### Relative Questions: 1. What are the roots of $$f(x) = 0$$? 2. How does the function behave at the critical points? 3. What is the range of $$f(x)$$? 4. How does the absolute value affect the symmetry of the function? 5. Can we use this function to model any physical phenomena? **Tip**: When working with absolute values in functions, always break the analysis into intervals where the expression inside the absolute value is positive and negative.

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Math Problem Analysis

Mathematical Concepts

Absolute Value
Quadratic Equations
Piecewise Functions
Function Analysis

Formulas

Absolute value property: |a| = a if a ≥ 0; |a| = -a if a < 0
Quadratic equation: ax^2 + bx + c
Vertex formula for quadratics: x = -b / (2a)

Theorems

Properties of absolute values
Quadratic function behavior based on coefficients

Suitable Grade Level

Grades 10-12