Given , , and , find the minimum value of .
Solution
To find the minimum value of given , , and , we proceed as follows:
1. First, we express in terms of the inverses of and :
2. Recognizing that , we can multiply the sum of inverses by a clever form of (which is ) to facilitate the use of the AM-GM inequality:
3. Simplify the expression by distributing and rearranging terms:
4. Apply the AM-GM inequality, , to the terms and :
5. Simplify the expression under the square root and the inequality:
6. The equality holds (which means we have found the minimum) if and only if , or equivalently . Solving this together with gives and .
Therefore, the minimum value of , given the conditions, is .
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