已知x/3=y=z/2≠0,则2x^2-2y^2+5z^2/xy+yz+zx
问题描述：
已知x/3=y=z/2≠0,则2x^2-2y^2+5z^2/xy+yz+zx
答
已知x/3=y=z/2≠0,∴x=3y,x²=9y²；z=2y,z²=4y².(2x²-2y²+5z²)/(xy+yz+zx)=(18y²-2y²+20y²)/(3y²+2y²+6y²)=(36y²)/(11y²)=36/11=3又3/1...