已知x y z 满足x+y=5,z²=xy+y-9,求x+2y+3z的值
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![已知x y z 满足x+y=5,z²=xy+y-9,求x+2y+3z的值](/uploads/image/z/6890757-69-7.jpg?t=%E5%B7%B2%E7%9F%A5x+y+z+%E6%BB%A1%E8%B6%B3x%2By%3D5%2Cz%26%23178%3B%3Dxy%2By-9%2C%E6%B1%82x%2B2y%2B3z%E7%9A%84%E5%80%BC)
已知x y z 满足x+y=5,z²=xy+y-9,求x+2y+3z的值
已知x y z 满足x+y=5,z²=xy+y-9,求x+2y+3z的值
已知x y z 满足x+y=5,z²=xy+y-9,求x+2y+3z的值
x+y=5
x=5-y
z^2=xy+y-9
z^2=(5-y)y+y-9
z^2=-y^2+6y-9
z^2=-(y-3)^2
z^2+(y-3)^2=0
所以,z=0,y-3=0
z=0,y=3
x=5-y=5-3=2
x+2y+3z=2+2*3+3*0=8