JAMB 2010 Mathematics · Question 4
If x * y = x + y, find then value of (2*3)*5
Options
- A.36
- B.25
- C.11
- D.55
Answer: A. 36
Explanation written with AI and checked against the answer key
Analyze the question: The symbol * is a custom operation, defined as x * y = x + y². We must apply the rule twice: first to the bracket (23), then use that result with 5. Concept: In a defined operation x * y = x + y², the first number is taken as it is, and the second number is squared. **Step 1: Work out the bracket (23)** Here x = 2 and y = 3: 2 * 3 = 2 + 3² = 2 + 9 = 11 Step 2: Work out 11 * 5 Here x = 11 and y = 5: 11 * 5 = 11 + 5² = 11 + 25 = 36 Answer: (23)5 = 36, which is option A. Tip: With defined operations, always solve the bracket first, then substitute the result into the rule again. Be careful about which variable is squared: only y is squared, not x. Reversing the order would give a different answer, since this operation is not commutative.AI can make mistakes. Report anything that looks wrong.
Past questions © the examination body (JAMB/WAEC/NECO). DeeepSolve is not affiliated with them. Rights holders: see /copyright.