Basic Mathematics05 marksNumerical: local extreme valuesLocal extrema of multivariable functions
Find the local extreme values of the function f(x,y) = xy - x2 - y2 - 2x - 2y + 4.
Find the local extreme values of the function $f(x,y) = xy - x^2 - y^2 - 2x - 2y + 4$. [5]
Function: $f(x,y) = xy - x^2 - y^2 - 2x - 2y + 4$ First partial derivatives: $$fx = y - 2x - 2$$ $$fy = x - 2y - 2$$ Set equal to zero: $$y - 2x - 2 = 0 \quad (1)$$ $$x - 2y - 2 = 0 \quad (2)$$ From (1): $y = 2x + 2$ Substitute into (2): $$x - 2(2x+2) - 2 = 0$$ $$x - 4x - 4 - 2 = 0$$ $$-3x - 6 = ...