若x-y=9,xy=7/4,则x+y=?

|x|/x+y/|y|+xy/|xy|= 若x-y=4,xy=1,则(2x+y-2xy)-(3x+2y+xy)-(4xy+3y-5x)= 已知x-y=3xy,且xy不等于0,则-3x+6xy+3y/(7x-5y)-9xy-(3x-y) 若x-y=9,xy=7/4,则x+y=? 已知（x+y)^2=9,x^2+y^2=7,则xy=?已知（x+y)^2=9,x^2+y^2=7,则xy=?已知（x+y)^2=4,（x-y）^2=3,则x^2+y^2=?若x^2+y^2=3,xy=1,则x-y=? 若2x^2-6xy+9y^2-4x+4=0,则y/x-x/y=若2x^2-6xy+9y^2-4x+4=0,则y/x-x/y=? 若x.y>0,9x+y=xy,则x+y的最小值为? 若x.y>0,9x+y=xy,则x+y的最小值为? 若x、y∈R+,4x+y=xy,则x+y的最小值为 化简:(x+y-4xy/x+y)*(x-y-4xy/x-y)= 若|x-3|+（y+2）=0,则（x-y+4xy/x-y）（x+y-4xy/x+y）的值是 若|x-3|+（y+2）²=0,则（x-y+4xy/x-y）（x+y-4xy/x+y）的值是 当实数x,y满足xy+x+y+7=0,3x+3y=9+2xy,则x平方y+xy平方=多少 若xy/(x+y)=3,则(6x+4xy+6y)/(9x+4xy+9y)=______ 若x+y=8,xy=7,球3xy-x-y+4的值 若x-y/x+y=2,则x2+2xy+y2/4xy=多少 已知正数x y满足xy=x+9y+7 则xy的最小值是 若正数xy满足x+y=xy,则x+4y的最小值