当4x-3y-6z=0,x=2y-7z=0时,求(x方+2y方+5z方)/(x方+3y方+z方)快
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![当4x-3y-6z=0,x=2y-7z=0时,求(x方+2y方+5z方)/(x方+3y方+z方)快](/uploads/image/z/810886-22-6.jpg?t=%E5%BD%934x-3y-6z%3D0%2Cx%3D2y-7z%3D0%E6%97%B6%2C%E6%B1%82%EF%BC%88x%E6%96%B9%2B2y%E6%96%B9%2B5z%E6%96%B9%EF%BC%89%2F%28x%E6%96%B9%2B3y%E6%96%B9%2Bz%E6%96%B9%EF%BC%89%E5%BF%AB)
当4x-3y-6z=0,x=2y-7z=0时,求(x方+2y方+5z方)/(x方+3y方+z方)快
当4x-3y-6z=0,x=2y-7z=0时,求(x方+2y方+5z方)/(x方+3y方+z方)
快
当4x-3y-6z=0,x=2y-7z=0时,求(x方+2y方+5z方)/(x方+3y方+z方)快
4x-3y-6z=0 (1)
x+2y-7z=0 (2)
(1)*2+(2)*3
8x+3x-12z-21z=0
z=x/3
(1)*7-(2)*6
28x-6x-21y-12y=0
y=2x/3
所以y²=(4/9)x²,z²=(1/9)x²
所以原式=[x²+(8/9)x²+(5/9)x²]/[x²+(12/9)x²+(1/9)x²]
=(22/9)x²/(22/9)x²
=1