JAMB 2013 Mathematics · Question 5

Solve for x: |x - 2| < 3

Options

  1. A.x < 5
  2. B.-2 < x < 3
  3. C.-1 < x < 5
  4. D.x < 1

Answer: C. -1 < x < 5

Explanation written with AI and checked against the answer key

Analysis

The question asks us to solve an inequality involving an absolute value: ∣x−2∣<3|x - 2| < 3.

Concept

The absolute value of a number represents its distance from zero on a number line. When we have an inequality of the form ∣f(x)∣<a|f(x)| < a (where a>0a > 0), it means the expression inside the absolute value must be between −a-a and aa.

Mathematically, this translates to: −a<f(x)<a-a < f(x) < a

Solution

Given the inequality: ∣x−2∣<3|x - 2| < 3

Step 1: Rewrite the inequality without the absolute value bars. Based on the principle above, we set the expression between −3-3 and 33: −3<x−2<3-3 < x - 2 < 3

Step 2: Isolate xx. To get xx by itself in the middle, we need to add 22 to all three parts of the inequality: −3+2<x−2+2<3+2-3 + 2 < x - 2 + 2 < 3 + 2

Step 3: Simplify. −1<x<5-1 < x < 5

This means xx must be greater than −1-1 and less than 55.

Conclusion

Comparing our result to the given options: A. x<5x < 5 B. −2<x<3-2 < x < 3 C. −1<x<5-1 < x < 5 D. x<1x < 1

The correct option is C.

Exam Tip

Whenever you see an absolute value inequality with a "less than" sign (<<), remember the acronym "LESS THAN = BETWEEN". This reminds you that the solution will be a range trapped between two values. If the sign were "greater than" (>>), the solution would be "OR" (pointing outwards away from the center).

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