x+y=12,xy=9求x²+xy²分之x²+3xy+y²

x+y=12,xy=9求x²+xy²分之x²+3xy+y²
x+y=12,xy=9求x²+xy²分之x²+3xy+y²

x+y=12,xy=9求x²+xy²分之x²+3xy+y²
(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

x05-3xy-4y05=0 x^2-3xy-4y^2=0 (x/y)^2-3(x/y)-4=0 (x/y-4)(x/y+1)=0 x/y=4 x/y=-1

X分之21