题目设z=u^2+v^2,u=x+2y,v=x-2y，则(partial z)/(partial x)=（ ）A. 4u-2vB. 4u+2vC. 2u-2vD. 2u+2v设$z=u^{2}+v^{2}$,$u=x+2y,v=x-2y$，则$\frac{\partial z}{\partial x}=$（ ）A. 4u-2vB. 4u+2vC. 2u-2vD. 2u+2v题目解答答案D. 2u+2v