find relative extrema for f(x, y) = 10^(xy)

joi

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Jul 10, 2006
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Find the relative extrema for f(x, y) = 10^(xy).

So far, I have found the critical points by finding the partials with respect to x, and then with respect to y.

. . .Partial with respect to x: (ln10)(10^(xy))(y)
. . .Partial with respect to y: (ln10)(10^(xy))(x)

I then set the two equal to each other and tried to solve for x and y. Since 10^(xy) can never be zero, the only way for either expression to be zero is if x and y are themselves zero. Therefore, my critical point resulted in being (x, y) = (0, 0).

Then I had to classify the extrema using the 2nd partial test. The equation I used was:

. . .d = (fxx)(fyy)-[fxy]^2

I got everything (fxx, fxy, and fyy) to come out to be 0. When I plugged into d, I got the answer that the test was inconclusive. This doesn't seem right so I thought it wise to get a second opinion.

Thank you!
 
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