已知2005x^3=2006y^3=2007z^3,且1/x+1/y+1/z=1,说明3√2005x^2+2006y^2+2007z^2=3√2005+3√2006+3√2007.说明：2005x^3是三次方,3√2005x^2+2006y^2+2007z^2整个式子开3次方.3√2005也是开三次方.

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