因为x^3+x^7>=2√(x^3*x^7)=2x^5y^4+y^8>=2y^6z^5+z^9>=2z^7所以x^3+y^4+z^5+x^7+y^8+z^9>=2(x^5+y^6+z^7)而x^3+y^4+z^5+x^7+y^8+z^9=60=2(x^5+y^6+z^7)所以不等式x^3+x^7>=2x^5,y^4+y^8>=2y^6,z^5+z^9>=2z^7均取等...