11.3.5. z = 3x^2 + xy - y^2 + 1; M0(2;1); Δx = 0.1; Δy = 0.2.
[m] z`_{x}=(3x^2+xy-y^2+1)`_{x}=6x+y[/m]
[m] z`_{y}=(3x^2+xy-y^2+1)`_{y}=x-2y[/m]
[m] z`_{x}(M_{o})=6\cdot 2+1=13[/m]
[m] z`_{y}(M_{o})=2-2\cdot1=0[/m]
[m]Δ z (M_{o}) ≈ 13\cdot 0,1+0\cdot 0,2=1,3[/m]
О т в е т. [b]1,3[/b]