问题描述： 若x/3=y/2=z/5则x^2-y^2-z^2/（xy+yz+zx） 1个回答 分类：数学 2014-11-06 问题解答： 我来补答 设x/3=y/2=z/5=t,则x=3t,y=2t,z=5t(x²-y²-z²)/(xy+yz+zx)=[(3t)²-(2t)²-(5t)²]/(3t×2t+2t×5t+5t×3t)=(9t²-4t²-25t²)/(6t²+10t²+15t²)=(-20t²)/(31t²)= -20/31 展开全文阅读
