Exams › JEE Advanced › Maths
For a, b belonging to the positive reals, find the minimum possible value of (a + b)*(1/a + 1/b).
- 4
- 2
- 1
- 8
Correct answer: 4
Solution
Expanding gives 2 + a/b + b/a. By AM-GM, a/b + b/a >= 2, so the whole expression is at least 4, achieved at a = b.
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