已知：x-y=5,z-y=3,求x^2+y^2+z^2-xy-yz-xz的值

来源：学生作业帮助网编辑：六六作业网时间：2024/11/28 15:17:21

已知：x-y=5,z-y=3,求x^2+y^2+z^2-xy-yz-xz的值已知：x-y=5,z-y=3,求x^2+y^2+z^2-xy-yz-xz的值已知：x-y=5,z-y=3,求x^2+y^2+

已知：x-y=5,z-y=3,求x^2+y^2+z^2-xy-yz-xz的值
已知：x-y=5,z-y=3,求x^2+y^2+z^2-xy-yz-xz的值

已知：x-y=5,z-y=3,求x^2+y^2+z^2-xy-yz-xz的值
x-y=5,z-y=3
两式想减得
x-z=2
x^2+y^2+z^2-xy-yz-xz
=1/2(2x^2+2y^2+2z^2-2xy-2yz-2xz)
=1/2(x-y)²+1/2(z-y)²+1/2(x-z)²
=1/2(25+9+4)
=19

所求式子可以转化成(（x-y)^2+(y-z)^2+(z-x)^2)/2-3/2
由已知可知，x-y=5
z-y=3
x-z=2
代入得（5^2+3^2+2^2）/2-3/2=35/2

已知(x+y)(x+z)=x,(y+z)(y+x)=2y,(z+x)(z+y)=3z,求x,y,z 已知{x-5y+2z=0 3x-5y-4z=0,求x：y:z 已知2x+5y+4z=6 3x+y-7z=-4求x+y-z 已知x/4=y/5=z/6 求x+y+z/3x-2y+z的值已知x/4=y/5=z/6,求x+y+z/3x-2y+z的值. 已知x:y:z=1:3:5,求（2x+3y-z)/(x+y-2z)的值已知X:Y:Z=3:4:5,求4X+3Y-2Z/X+Y+Z的值已知x:：y：z=3：4：5,(1)求x+y分之z的值；（2）若x+y+z=6,求x,y,z. 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3X=4X,5Y=6Z求X+Y：Y+Z 已知z、y、z同时满足x+3y-5z=0,2x-y-3z=0,求x:y:z 已知x+y-z=0,2x-y+2z=0 求（3x-2y+5z)/(5x-3y+2z)的值已知x+4y+3z=3x-2y-5z=0,求x+2y-z/2x-3y+7z的值已知4x-3y-6z=0,x+2y-7z=0,求5x+2y-z/2x-3y-10z 已知x+2y-3z=0,2x+3y+5z=0,求(x+y+z)除以（x-y+z) 已知x+2y-3z=0,2x+3y+5z=0,求(x+y+z)除以（x-y+z) 已知:x+y+z=0,5x-3y-z=0,求:5x-y+z/2x+8y+7z 的值