解方程组xy+xz=8-x^2,yx+yz=12-y^2,zy+zx=-4-z^2解方程组xy+xz=8-x^2,yx+yz=12_数学解答

解方程组xy+xz=8-x^2,yx+yz=12-y^2,zy+zx=-4-z^2
解方程组xy+xz=8-x^2,yx+yz=12-y^2,zy+zx=-4-z^2

人气：351 ℃　时间：2020-05-31 05:54:25

解答

xy+xz=8-x² yx+yz=12-y² zy+zx=-4-z²x(x+y+z)=8 y(x+y+z)=12 z(x+y+z)=-4(x+y+z)²=8+12-4=16x+y+z=±4则①x+y+z=4时 x=4-y-z 代入yx+yz=12-y²和 zy+zx=-4-z²,则y=3 z=-1则x=2,y=3,z=-...