14.3-bo'lim: Nisbiy minimal va maksimallar

Quyidagi funksiyalarning barcha kritik nuqtalarini toping va tasniflang.

1. \(f\left( {x,y} \right) = \left( {y - 2} \right){x^2} - {y^2}\) Yechim
2. \(f\left( {x,y} \right) = 7x - 8y + 2xy - {x^2} + {y^3}\) Yechim
3. \(f\left( {x,y} \right) = \left( {3x + 4{x^3}} \right)\left( {{y^2} + 2y} \right)\) Yechim
4. \(f\left( {x,y} \right) = 3{y^3} - {x^2}{y^2} + 8{y^2} + 4{x^2} - 20y\) Yechim