x+y+Z=50 1500x+2100y+2500z=90000

方程组{x+y+z=50,1500x+2100y+2500z方程组是{x+y+z=50,1500x+2100y+2500z=90000 三元一次方程组 1500x+2100y+2500z=90000 x+y+z=50 x+y+Z=50 1500x+2100y+2500z=90000 (x+y-z)(x-y+z)= X+Y+Z=? x/y=(x+z)/(y+z)y/z=(x+y)/(x+z) 已知 x/(y+z)+y/(z+x)+z/(x+y)=1求 (x*x)/(y+z)+(y*y)/(x+z)+(z*z)/(x+y)=? (y+z)/x=(z+x)/y=(x+y)/z求x+y-z/x+y+z的值 z+=x>y?++x: x=y; y=z; z=x/y 解方程 Y=X+Z Y-Z=2 100Z+10Y+X-(100X+10Y+Z)=99 Y=X+ZY-Z=2100Z+10Y+X-(100X+10Y+Z)=99 解三元一次方程组x+y=50-z 1500x+2100y=90000-2500z 求{X+Y+Z=50 {1500X+2100Y+2500Z=90000 方程组的正整数解 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+u)=y/(z+u+x)=z/(u+y+x)=u(x+y+z)求(x+y)/(z+u)+(y+z)/(y+x)+(z+y)/(x+y)+(u+x)/(z+y) 已知(x+y)(x+z)=x,(y+z)(y+x)=2y,(z+x)(z+y)=3z,求x,y,z fangchengzu:X+Z=Y 7Z=X+Y+Z X+Y+Z=14 若z分之x+y+z=y分之x-y+z=x分之-x+y+z,求xyz分之(x+y)(y+z)(z+x)