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Printjmc
algebra senior
Problem
The smallest distance between the origin and a point on the graph of can be expressed as , where and are positive integers such that is not divisible by the square of any integer greater than one. Find .
Solution
By the distance formula, we are trying to minimize . In general, minimization problems like this require calculus, but one optimization method that sometimes works is to try to complete the square. Pulling out a factor of from under the radical, we have This last expression is minimized when the square equals , i.e. when . Then the distance is . Hence the desired answer is .
Final answer
12