dz/dx=у/(2sqrt(х))-1 d^2z/dx^2=((1'2sqrt(х)-(2sqrt(х))'\(2sqrt(х))^2))y+1\2sqrt(х)=1\sqrt(х)\2х



dz/dy=sqrt(х)-4у+14 d^2z/dу^2=1\2sqrt(х)-4




dz/dydx=y'sqrt(х)+(sqrt(х))'y-2*2y-1+14=sqrt(х)+y\2sqrt(х)-4y+13
d^2z/dxdy=1\2sqrt(х)+((y'2sqrt(х)-(2sqrt(х))'y)\(2sqrt(х))^2)-4