此题Z=x/[(X^2+Y^2)^(1/2)]答案是fx(x,y)=(y^2)/[(x^2+y^2)^(3/2)];fy(x,y)=-xy/[(x^2+y^2)^(3/2)],（属于《简明微积分》第二版,李亚杰主编）（最好能用草稿纸写上详细过程。机体字确实看得头晕目眩。见谅！）

1、y-x/x²-y²2、(x-y)(y-z)(z-x)/(z-y)(y-x)(x-z) 若有理数x,y,z满足√x+√y-1+√z-2=1/2(x+y+z) 确定(x-yz)^3若有理数x,y,z满足√x+√y-1+√z-2=1/2(x+y+z) 确定(x-yz)^3的值其中（y-1) (z-2)都在根号下此题是竞赛初试中的问题，应该不是太难的。辛苦了。 已知实数x y z满足x/(x+1)=y/(y+2)=z/(z+3)=(x+y+z)/3,求x+y+z的值 已知实数x y z满足x/(x+1)=y/(y+2)=z/(z+3)=(x+y+z)/3,求x+y+z的值 已知整数x,y,z满足x≤y≤z,且|x+y|+|y+z|+|z+x|=4,|x-y|+|y-z|+|z-x|=2那么x²+y²+z²的值等于（ ）.A.2 B.14 C.2或14 D.14或17注：此题x≤y≤z,不是x≤y＜z! x*z/(20+x+y)=3; z/(20+x+y/2)=0.45; x*z /(x+20)=9; 请问此方程如何解 x+y+z=1 x+3y+7z=-1 x+5y+8=2题错了 x+y+z=1 x+3y+7z=-1 x+5y+8z=2 用行列式的性质证明：y+z z+x x+y x y z x+y y+z z+x =2 z x y z+x x+y y+z y z x 这个怎么证? x+y+z=6 x+2y+3z=14 y+1=z 若|x+3|+|y-2|+|2×z+1|=0求(x×z-y×z)(y-x+z)的值 六年级三道关于方程的数学题. 解方程组{-x+2y+3z=12 {2x-2y+5z=13 {3x+2y+z=10 解方程组{2(x+y)-3(x-y)=1 {6(x+y)+7(x-y)=51 此题去括号,变简易方程组再做.已知方程组{2x-y=0 {2x+y=m 和方程组{x-y=5 {2x-y=n-1 (x-2y+z)(x+y-2z)分之（y-x)(z-x) + (x+y-2z)(y+z-2x)分之(z-y)(x-y) + (y+z-2z)(x-2y+z)分之（x-z)(y-z)=?第三部分那个是 （y+z-2x)(x-2y+z)分之（x-z)(y-z) 试证明(x+y-2z)+(y+z-2x)+(z+x-2y)=3(x+y-2z)(y+z-2x)(z+x-2y) 已知：x^2/(z+y)+y^2/(x+z)+z^2/(x+y)=0,求x/(z+y)+y/(x+z)+z/(x+y)的值. x^2/(z+y)+y^2/(x+z)+z^2/(x+y)=0,求x/(z+y)+y/(x+z)+z/(x+y)的值 已知(x+y)(x+z)=x,(y+z)(y+x)=2y,(z+x)(z+y)=3z,求x,y,z 几道三元一次方程组1.{5x-3y+z=2{5x+2y-4z=3{-5x+y-z=2(此处是大括号.由于打不出,将就下八~以下都是如此）2.{x-y-z=-1{3x+5y+7z=11{4x-y+2z=-1 分式加减的几道题目求速度1 .(x+y)²/（x-z)(y-z) - (y+z)²/（x-z)(y-z) = 2.2x+3y/x-y+2y/y-x-3y/x-y=