Math Problem Statement

Solve the rational inequality: (2x - 8) / (x - 2) ≥ 0

Solution

The inequality shown in the image is a rational inequality:

2x8x20\frac{2x - 8}{x - 2} \geq 0

Step-by-Step Solution:

  1. Factor the numerator: 2x8=2(x4)2x - 8 = 2(x - 4) So the inequality becomes: 2(x4)x20\frac{2(x - 4)}{x - 2} \geq 0

  2. Find the critical points: The critical points come from where the numerator or the denominator is equal to zero:

    • Numerator: 2(x4)=02(x - 4) = 0 gives x=4x = 4.
    • Denominator: x2=0x - 2 = 0 gives x=2x = 2 (Note: x=2x = 2 is undefined for the rational function, as it makes the denominator zero).
  3. Sign analysis on intervals: The critical points divide the real number line into three intervals: (,2),(2,4),(4,)(-\infty, 2), (2, 4), (4, \infty) We will test the sign of the expression in each of these intervals.

    • For x(,2)x \in (-\infty, 2): Choose x=0x = 0: 2(04)02=2(4)2=4>0\frac{2(0 - 4)}{0 - 2} = \frac{2(-4)}{-2} = 4 > 0
    • For x(2,4)x \in (2, 4): Choose x=3x = 3: 2(34)32=2(1)1=2<0\frac{2(3 - 4)}{3 - 2} = \frac{2(-1)}{1} = -2 < 0
    • For x(4,)x \in (4, \infty): Choose x=5x = 5: 2(54)52=2(1)3=23>0\frac{2(5 - 4)}{5 - 2} = \frac{2(1)}{3} = \frac{2}{3} > 0
  4. Inclusion of critical points:

    • At x=4x = 4, the expression is 042=0\frac{0}{4 - 2} = 0, which satisfies the inequality.
    • At x=2x = 2, the function is undefined, so x=2x = 2 is not included in the solution.
  5. Final solution: The solution is where the expression is non-negative, which includes the intervals where the expression is positive or zero: (,2)[4,)(-\infty, 2) \cup [4, \infty)

Final Answer:

x(,2)[4,)x \in (-\infty, 2) \cup [4, \infty)

Would you like more details on any of these steps? Here are 5 related questions to extend this concept:

  1. How do you solve rational inequalities with multiple factors in the numerator and denominator?
  2. What happens if the inequality was 2x8x2>0\frac{2x - 8}{x - 2} > 0 instead of 0\geq 0?
  3. How would you solve a rational inequality where both the numerator and denominator are quadratic?
  4. Can you explain how to graph the solution to this inequality on a number line?
  5. How does the process change if the inequality was less than zero (<0< 0) instead of greater than or equal?

Tip: Always remember to check for points where the denominator equals zero in rational inequalities—these points must be excluded from the solution!

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Math Problem Analysis

Mathematical Concepts

Algebra
Rational Inequalities
Sign Analysis

Formulas

Sign Analysis for Rational Functions
Critical Points of Rational Functions

Theorems

Sign Change Theorem
Properties of Inequalities

Suitable Grade Level

Grades 10-12