z(x,y) = -18xy -3x^2y -9x^2 -6xy^2 -\frac{21}{4}y^3 -\frac{117}{4}y^2 -54y + 3

Uh oh! Wolfram|Alpha doesn't run without JavaScript.

Please enable JavaScript. If you don't know how, you can find instructionshere.Once you've done that, refresh this page to start using Wolfram|Alpha.