36*[a^2+b^2+c^2]=900
60*[ax+by+cz]=1800
25*[x^2+y^2+z^2]=900
所以36*[a^2+b^2+c^2]-60*[ax+by+cz]+25[x^2+y^2+z^2]=0
所以（36a^2-60ax+25x^2）+（36b^2-60by+25y^2）+（36c^2-60cz+25z^2）=0
即（6a-5x）^2+（6b-5y）^2+（6c-5z）^2=0
即6a=5x 6b=5y 6c=5z
即a=5/6x b=5/6y c=5/6z代入2007a+5b+8c/2007x+5y+8z
得2007a+5b+8c/2007x+5y+8z=5/6