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Somefantastik

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I've got a function that I'm trying to show is positively invarient.

[tex] Let \ V(x,y) = 0.45x^{2}+xy+0.56y^{2} > 0 \ for \ all \ x,y \ in \ R^{2} [/tex]

[tex] V'(x,y) = ... = -8.4840x^{2} - 18.7412x - 10.3496 - 0.011xy - 0.011y^{2}; [/tex]

How can I find a neighborhood/region that makes V'(x,y)< 0?