x+y=3 y+z=4 x+z=5怎么做

x+y=3 y+z=4 x+z=5怎么做 x+y/z=y+z/x=z+x/y=k怎么做 x=3,y=4,z=5,求以下表达式的值,怎么算 (x && y)==(x || z) (x>y)+(y!=z) || (x+y)&&(y-z) x++ -y+(++z) 3元一次方程5x+4y+z=0,3x+y-4z=11,3+y+z=-2怎么做 (x+y):(y+z):(z+x)=3:4:5 3x+y-z=-4已知(x+y):(y+z):(z+x)=3:4:5 ；3x+y-z=-4求x y z 已知x-y=3,y-z=,则（x-z）2+5（x-z）+25/4的值等于?(说明怎么做的） {x:y:z=3:4:5 {x+2y+z=48 怎么解 (4x-2y-z)-{5x-[8y-2z-(x-2y)]-x-(3y-10z)}=? x+y-z=3 y+z-x=5 z+x-y=7 求x,y,z 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=4,x-y+z=0,x-z=8怎么解? (x+y-z)(x-y+z)= x+y/2=z+x/3=y+z/4 x+y+z=27 x/2=y/3=z/5 x+3y-z/x-3y+z 设|x|-|y|+|z|=|x+y+z|,且|x+y|=4,|y+z|=5,|y|=3,求(x-y-z)^2的值 x+2y=3x+2z=4y+z 求x:y:z 怎么做3元一次方程2x+3y+z=6x-y+2z=1x+2y-z=5 (4x-2y-z)-{5x-[8y-2z-(x+y)]-2(3y-10z)}=?好难啊