Difficulty: Medium
Correct Answer: ± 8
Explanation:
Introduction / Context:
The original database text was garbled. Using the Recovery-First Policy, we interpret it as a classic rational-expression identity: (x + 4)/(x − 4) + (x − 4)/(x + 4) = 10/3. This kind of expression simplifies via a common denominator, producing an equation only in x^2. We then solve for x and check domain restrictions (x ≠ ±4).
Given Data / Assumptions:
Concept / Approach:
Use the identity (A/B) + (B/A) = (A^2 + B^2)/(AB). Here, A = x + 4 and B = x − 4. This yields a rational equation in x that simplifies to a quadratic in x^2. Solve and select the real roots allowed by the domain.
Step-by-Step Solution:
Verification / Alternative check:
Denominator check: x ≠ ±4, so ±8 are valid. Substitute x = 8 (or −8) to confirm the left-hand side equals 10/3 numerically.
Why Other Options Are Wrong:
±4 are excluded (division by zero). ±6 and 2 ± √3 do not satisfy the equation when substituted. “No real root” is false since ±8 work.
Common Pitfalls:
Dropping the domain restriction, or algebra errors when simplifying the rational sum can lead to spurious answers.
Final Answer:
± 8
Discussion & Comments