4x+y=40 4y+z=55 5x-z=20 求X等于多少

3x+7y+4z=35,x+5y+2z=40,x+y+z=( ) (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 x+y+z=4x-5y=y-x+6z,xyz不等0,x:y:z=? (4x-2y-z)-{5x-[8y-2z-(x-2y)]-x-(3y-10z)}=? x+y+z=77 y+5=z 4x=z三元一次方程组 X/4=Y/5=Z/7则x+y+z/z=? 一道数奥题,(x+y-z)²+(y+z-4)=-|z+x-5| 设|x|-|y|+|z|=|x+y+z|,且|x+y|=4,|y+z|=5,|y|=3,求(x-y-z)^2的值 已知x:4=y:5=z:6.则x:y:z= (x+y):(y+z)= (4x-2y-z)-{5x-[8y-2z-(x+y)]-2(3y-10z)}=?好难啊 x+y/2=z+x/3=y+z/4 x+y+z=27 x-4y+z=-302x+y-z=18x--y-z=7 14x+4y+z=200,x+y+z=100求解x,y,z x+2y=3x+2z=4y+z 求x:y:z 若x,y,z成等差数列,则(z-x)^2-4(x-y)(y-z)= (x*x+2)(y*y+4)(z*z+8)=64xyz,求x,y,z 解三元一次方程组：(1)x+2y+3z=11x-y+4z=10x+3y+2z=2(2)x:y=3:5y:z=5:6x+y+2z=40(3)x+y-z=2y+z-x=4z+x-y=6谢谢! x+y=5 2x+3y-z=9 x-y+z=4