x+y=12,xy=9求x²+xy²分之x²+3xy+y²_数学解答

x+y=12,xy=9求x²+xy²分之x²+3xy+y²

人气：377 ℃　时间：2019-10-31 22:31:59

解答

(x²+3xy+y²)/(x²y+xy²)
=(x²+2xy+y²+xy)/[xy(x+y)]
=[(x+y)²+xy)/[xy(x+y)]
=(12²+9)/(9*12)
=(144+9)/108
=153/108
=17/12