已知x,y,z满足x+y=5,z^2=xy+y-9 求x+2y+3z的值

来源：学生作业帮助网 编辑：六六作业网 时间：2024/11/15 06:18:26
已知x,y,z满足x+y=5,z^2=xy+y-9求x+2y+3z的值已知x,y,z满足x+y=5,z^2=xy+y-9求x+2y+3z的值已知x,y,z满足x+y=5,z^2=xy+y-9求x+2y

已知x,y,z满足x+y=5,z^2=xy+y-9 求x+2y+3z的值
已知x,y,z满足x+y=5,z^2=xy+y-9 求x+2y+3z的值

已知x,y,z满足x+y=5,z^2=xy+y-9 求x+2y+3z的值
x=5-y
z2=(5-y)y+y-9
=6y-y2-9
=-(9-6y+y2)
=-(y-3)2
由题意,只有当该项为0时等式成立
得y=3
那么z=0 x=2
即原式=2+6+0=8

x=5-y z2=-(y-3)2 y=3 z=0 x=2
=2+6+0=8

z^2=(5-y)y + y -9 = 5y-y^2+y-9 = -(y^2-6y+9) = -(y-3)^2
所以，z^2 = -(y-3)^2, 所以z=0, y-3=0
所以 y=3, x=2
所以 x+2y+3z = 2 + 2*3 + 0*3 = 8

已知x,y,z,满足方程组x-2y+z=0,7x+4y-5z=0 已知z、y、z同时满足x+3y-5z=0,2x-y-3z=0,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x、y、z满足方程组：x+y-z=6；y+z-x=2；z+x-y=0 求x、y、z的值 已知X.Y.Z满足方程组,X+y-Z=6y+z-x=2z+x-y=0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x,y,z,满足2/x=3/(y-z)=5/(z+x),则(5x-y)/(y+2z)的值为多少? 已知x.y.z满足x-2y+z=0且7x+4y-5z=0,求x:y:z的值 已知x、y、z满足x—2y+z=0 7x+4y—5z=0 ,求x：y：z 已知x,y,z,同时满足方程x+3y-5z=0,2x-y-3z=0求x：y：z的值 已知x,y,z满足方程组x-2y+z=0 7x+4y-5z=0求x:y:z的值 已知x、y、z满足{x-2y+z=0;7x+4x-5z=0,求x:y:z的值. 已知整数x、y、z,满足x≤y＜z,且｜x+y｜+｜y+z｜+｜z+x｜=4,｜x-y｜+｜y-z｜+｜z-x｜=2,求x^2+y^2+z^2的值. 已知整数x,y,z满足x≤y＜z,且|x+y|+|y+z|+|z+x|=4 |x-y|+|y-z|+|z-x|=2 那么x²+y²+z²的值 已知x,y,z满足方程组｛x+y-z=6{y+z-x=2{z+x_y=0,求x,y,z的值 已知x,y,z满足2/x=3/y-z=5/z+x,则5x-y/y+2x的值快快 已知x,y,z满足方程组：4x-5y+2z=o;x+4y-3x=0,求x:y:z的值 已知z不等于0,x、y、z满足4x-7y-5x=0,2x-y-z=0.求x：y