If a − b = 3 and a^2 + b^2 = 29, find ab.
Aptitude
Simplification
Difficulty: Easy
Choose an option
Answer
Correct Answer: 10
Explanation
Concept / Approach
- Use the identity (a − b)^2 = a^2 + b^2 − 2ab.
Step-by-step calculation(a − b)^2 = 3^2 = 9a^2 + b^2 − 2ab = 29 − 2ab = 92ab = 29 − 9 = 20 ⇒ ab = 10
Common pitfalls
- Using (a + b)^2 identity by mistake; here we need (a − b)^2.
Final Answer10