设x/3=y/4=z/6=k(k≠0)∴x=3ky=4kz=6k(xy+yz+zx)/(x²+y²+z²)=(3k*4k+4k*6k+6k*3k)/(9k²+16k²+36k²)=(54k²)/(61k²)=54/61如果您认可我的回答，请点击“采纳为满意答案”,祝学习进步！
