Difficulty: Easy
Correct Answer: 45
Explanation:
Introduction / Context:This problem uses algebraic identities that relate sums and differences to products. Specifically, knowing a^2 + b^2 and (a − b)^2 enables solving for ab via identity manipulations without finding a and b individually.
Given Data / Assumptions:
Concept / Approach:Use the identity (a − b)^2 = a^2 + b^2 − 2ab. Rearranging gives 2ab = (a^2 + b^2) − (a − b)^2. Substitute the given values to compute ab directly.
Step-by-Step Solution:
(a − b)^2 = a^2 + b^2 − 2ab144 = 234 − 2ab2ab = 234 − 144 = 90ab = 90 / 2 = 45Verification / Alternative check:If desired, we can choose numbers with product 45 that fit the constraints (not necessary here). The identity-based computation is sufficient and exact.
Why Other Options Are Wrong:
Common Pitfalls:
Final Answer:45
Discussion & Comments