Question

已知根号下x+y+3再+xy+x+y+2=0,则代数式y分之x+x分之y的值为

Answer 1

已知根号下x+y+3再+xy+x+y+2=0,根号下x+y+3=0,x+y= -3 xy+x+y+2=0,xy=1,将x+y= -3 两边平方得x^2+2xy+y^2=9,x^2+y^2=7 所以x/y+y/x=(x^2+y^2)/xy=7