若x+y-5xy=0,求(2x-3xy+2y)/(x+2xy+y)的值
问题描述：
若x+y-5xy=0,求(2x-3xy+2y)/(x+2xy+y)的值
答
x+y=5xy
（2x-3xy+2y)/(x+2xy+y）
=[2（x+y）-3xy]/[(x+y)+2xy]
=(2×5xy-3xy)/(5xy+2xy)
=7xy/7xy
=1若x＋1/x＝3,求(x^4＋x^2＋1)/x^2的值.（x＋1/x）²=x²+2+1/（x²）=9x²+1/(x²)=9-2=7你可以把(x^4＋x²＋1)/x²=x²[x²+1+1/（x²）]/x²约掉x²等于x²+1+1/（x²）=7+1=8希望采纳，不懂请追问！谢谢！