What is the value of to three significant digits such that the graphs of and intersect only once?
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Since the graphs intersect – actually touch – only once, the function values at the point of intersection have to match, but also the derivatives since otherwise the exponential graph would cross the line and there would be another intersection point.
We end up with the equations
x = t x ⇔ t = x x 1
1 = t x ln t
Plugging the first into the second gives
1 = x ⋅ ln ( x x 1 ) = x ⋅ x 1 ln x = ln x ⇔ x = e
Using the first equation, we get t to be
t = x x 1 = e e 1 ≈ 1 . 4 4 5 .