Difficulty: Easy
Correct Answer: 12
Explanation:
Problem restatement
Determine the common value of x that satisfies x = (√162 × √128) / x.
Given data
Concept/Approach
Use √a × √b = √(ab). Multiply both sides by x to obtain a quadratic in x.
Step-by-step calculation
x = √162 × √128 / x = √(162 × 128) / xx2 = √(20736) = 144x = √144 = 12 (taking the positive principal value)
Verification/Alternative
Check: √162 × √128 = √20736 = 144; then (144) / 12 = 12, which equals x.
Common pitfalls
Forgetting to combine radicals or missing that x appears in denominator; also note that in typical aptitude contexts, the positive root is expected.
Final Answer
12
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