The graphs of and intersect twice if and intersects never if . What's the value of ?
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If we let k = 1 / e , then the two graphs intersect at ( e e , e ) , and are also tangent at that point. A function y = x k with 0 < k < 1 / e will have a value smaller than e at x = e e , be greater than y = ln ( x ) at x = 1 , and will at some point overtake y = ln ( x ) , for k > 0 , because the derivative of y = x k is ever-increasing, whereas the derivative of y = ln ( x ) is ever-decreasing toward zero. Since both functions are continuous, then, by the intermediate value theorem, they must intersect twice. If k > 1 / e , then each function value (in the relevant domain) will be greater than that of k = 1 / e , and thus never intersect y = ln ( x ) .