已知x/2=y/3=z/4,求(xy+2yz-3xz)/(x^2+y^2+z^2)?
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![已知x/2=y/3=z/4,求(xy+2yz-3xz)/(x^2+y^2+z^2)?](/uploads/image/z/6890745-57-5.jpg?t=%E5%B7%B2%E7%9F%A5x%2F2%3Dy%2F3%3Dz%2F4%2C%E6%B1%82%28xy%2B2yz-3xz%29%2F%28x%5E2%2By%5E2%2Bz%5E2%29%3F)
已知x/2=y/3=z/4,求(xy+2yz-3xz)/(x^2+y^2+z^2)?
已知x/2=y/3=z/4,求(xy+2yz-3xz)/(x^2+y^2+z^2)?
已知x/2=y/3=z/4,求(xy+2yz-3xz)/(x^2+y^2+z^2)?
设x/2=y/3=z/4=t,则x=2t,y=3t,z=4t,
所以(xy+2yz-3xz)/(x^2+y^2+z^2)
=(6t^2+24t^2-24t^2)/(4t^2+9t^2+16t^2)
=6/29.