Question

高数求解，答案都看不懂？

若以下回答无法解决问题，邀请你更新回答

Answer 1

∂z/∂x=[1+2x/2√(x²+y²)]/[x+√(x²+y²)]
=[√(x²+y²)+x]/[x√(x²+y²)+(x²+y²)]
∂²z/∂x∂y={[y/√(x²+y²)·[x√(x²+y²)+(x²+y²)]-[√(x²+y²)+x]·[xy/√(x²+y²)+2y)]}/[x√(x²+y²)+(x²+y²)]²

追问

是先y后x啊