Evalute the first partial derivatives of the given function at the point (1,2,1)
#autox,y,z,t=var('x, y, z, t')f(x,y)=1-(x-1)^2-(y-2)^2P=plot3d(f,(x,-5,5),(y,-5,5),color='red')Q=implicit_plot3d(x==1,(x,-5,5),(y,-5,5),(z,-26,168))R=parametric_plot3d((1,t,-t^2+4*t-3),(t,-5,5),color='black',thickness=10)S=point3d((1,2,1),size=40,color='black')show(P+Q+R+S,figsize=(6,6))