Question

已知x,y满足x的平方+y的平方+五分之四=2x+y,求代数式xy分之x+y

Answer 1

已知x,y满足x^2+y^2+5/4=2x+y,求代数式xy/(x+y)

x^2+y^2+5/4=2x+y

x^2-2x+1+y^2-y+1/4=0

(x-1)^2+(y-1/2)^2=0

x-1=0,x=1

y-1/2=0,y=1/2

xy/(x+y)=1/3