设2000X^3=2001Y^3=2002Z^3,XYZ>0 且2000X^2=2001y^2=2002z^2=2000的立方 +2001的立方 +2002的立方,求x分之一+y分之一+z分之一的值.(提示:可设2000x^3=2001y^3=2002z^3=a,则2000x^2=x分之a,则2001y^2=y分之a,2002z^2=z分之a
问题描述:
设2000X^3=2001Y^3=2002Z^3,XYZ>0 且2000X^2=2001y^2=2002z^2=2000的立方 +2001的立方 +2002的立方,求x
分之一+y分之一+z分之一的值.(提示:可设2000x^3=2001y^3=2002z^3=a,则2000x^2=x分之a,则2001y^2=y分之a,2002z^2=z分之a
答
设2000x3=2001y3=2002z3=k 则2000x2=k/x 2001y2=k/y 2002z2=k/z2000的立方根=k的立方根/x 2001的立方根=k的立方根/y 2002的立方根=k的立方根/z由已知可得:(k/x+k/y+k/z)的立方根=k的立方根/x + k的立方根/y +k的立...