JAMB 2025 Mathematics · Question 52
Solve the inequality 2x + 3 > 5x + 8
Options
- A.x > 1
- B.x > -1
- C.x < -1
- D.x < 1
Answer: C. x < -1
Explanation written with AI and checked against the answer key
Analysis
The goal is to solve for in the linear inequality . Solving an inequality is very similar to solving an equation, but you must be careful when multiplying or dividing by a negative number, as that flips the inequality sign.
Concept
To solve this, we need to group the terms containing on one side and the constant terms on the other side.
Step-by-Step Solution
Step 1: Group the terms Subtract from both sides of the inequality to bring all terms to the left:
Step 2: Isolate the term Subtract from both sides:
Step 3: Solve for Divide both sides by . Important Rule: Whenever you divide or multiply an inequality by a negative number, you must reverse the inequality sign ( becomes ).
Step 4: Simplify the fraction
Converting the improper fraction to a mixed fraction: remainder So,
Conclusion
Comparing our result () with the given options, it matches option C.
Exam Tip
Always double-check your inequality sign when dealing with negative coefficients. A common mistake in JAMB is forgetting to flip the sign when dividing by a negative number, which would lead you to choose the wrong direction (like option B).
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