若4x-3y-6z=0,x+2y-7z=0(xyz=0),则代数式(5x^2+2y^2-z^2)/(2x^2-3y^2-10z^2)的值等于_____?
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若4x-3y-6z=0,x+2y-7z=0(xyz=0),则代数式(5x^2+2y^2-z^2)/(2x^2-3y^2-10z^2)的值等于_____?
若4x-3y-6z=0,x+2y-7z=0(xyz=0),则代数式(5x^2+2y^2-z^2)/(2x^2-3y^2-10z^2)的值等于_____?
若4x-3y-6z=0,x+2y-7z=0(xyz=0),则代数式(5x^2+2y^2-z^2)/(2x^2-3y^2-10z^2)的值等于_____?
4x-3y-6z=0 1)
x+2y-7z=0 2)
2)*4-1),得
11y-22z=0,y=2z
代入2),得
x+4z-7z=0,x=3z
将x,y代入分式,得
(45z^2+8z^2-z^2)/(18z^2-12z^2-10z^2)
=52z^2/-4z^2
=-13