Maxima and Minima of 2 variable closed

Question

Is the followIng case is possible  rt-s^2 > 0 and r= 0?

Comments

$rt-s^2$, what it means ?

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is this what you want to ask?

$rt-s^2>0$ and r=0 is not possible.

it simply means that, $-s^2>0$, which is not possible.

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thanks, @joshi_nitish.