若x,y∈(0,+∞),x+2y+xy=30 (1)求xy的取值范围（2）求x+y的取值范围若x,y∈(0,+∞),x+2y+xy=30(1)求xy的取值范围（2）求x+y的取值范围

若(x*x+y*y)(x*x+y*y)-4x*x*y*y=0,求代数式(x*x+5xy+y*y)/(x*x+2xy+y*y)的值 若x+y-5xy=0,求(2x-3xy+2y)/(x+2xy+y)的值 若2x+y=0,求(x^2+xy+y^2)/(2xy-x^2) 若集合{x,xy,lg(xy)}={0,|x|,y},求log8(x^2+y^2) 基本不等式及其应用若x,y∈（0,﹢∞）,且2x+8y-xy=0 ,则x + y的取值范围是-----------------------------------------------------------我的解法是；2x+8y=xy 2x+8y≥8√xy 即xy≥8√xy ,左右同时除以8√xy则得√xy≥8 若实数x,y满足x^2-xy-y^2 =0,则x/y=? 若正整数X,Y满足2X+Y--XY=0,求X+Y的最小值 已知x*x-4xy+4y*y=0 求[2x(x+y)-y(x+y)]/(4x*x-4xy+y*y)的值? 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 若x^2+xy+y=14,y^2+xy+x=28,求x+y 若x+y=1,x不等于0则x+(2xy+y^2)/x/(x+y)/x= 若根号x+y-3+绝对值xy+x+y-2=0,求x/y+y/x根号x+y-3+绝对值xy+x+y-2=0,求x/y+y/x 若1/x-1/y=2,求3x-2xy-3y/x-xy-y的值3x-2xy-3y/x-xy-y 不好意思，是3x-2xy-3y/x-2xy-y 若两个正实数x,y满足x^2+2xy-3y^2=0,求x^2+xy+y^2/x^2-xy+y^2 x,y∈(0,+∞),x+2y+xy=30,求x+y的取值范围 若X+Y=0,XY=11,求X^2-XY+Y^2的值. 若x,y满足x^+2y^-2xy+1=0,求xy的值