一直x^2-3xy=0

2y+3x=2xy(2y+3x)/(2xy)=1(1/x)+(3/y)=11≥2√(3/(xy))1≥12/(xy)xy≥12xy的最小值是12

3x*+xy-2y*=0（3x-2y）(x+y)=0那么x=2y/3或x=-yy/x=3/2或x/y=-1(x/y)-(y/x)-(x*+y*)/(xy)=(x/y)-(y/x)-(x/y+y/x)=

由y=3xy+x得x-y=-3xy2x+5xy-2y/x-2xy-y=2（x-y）+5xy/x-y-2xy=-6xy+5xy/-3xy-2xy1/5

1.2(Xy+Xy)-3(Xy-xy)-4Xy=2*2xy-0-4xy=4xy-4xy=02.1/2ab-5aC-(3acb)+(3aC-4aC)=1/2ab-5ac-3acb-ac=1/2ab-6a

y-x-2xy=0y-x=2xyx-y=-2xy(3x+xy-3y)/(y-xy-x)=[3(x-y)+xy]/[(y-x)-xy]=(-6xy+xy)/(2xy-xy)=-5xy/xy=-5

(-3x^y+2xy)-(4x^+xy)=-3x^y+2xy-4x^-xy=-3x^y+xy-4x^所以填上-3x^y+xy-4x^

析：首先可以由题看出,当x,y同号时可以取得最大值（因为异号时乘积小于0）.又由均值不等式得：1=x/3y/4>=2(x/3*y/4)^(1/2),解此不等式得：xy再问：写错了是R正再答：那就直接把

解(x+1)平方+/y-1/=0∴x+1=0,y-1=0∴x=-1,y=1∴2(xy-5xy平方)-(3xy平方-xy)=(2xy+xy)+(-10xy平方-3xy平方)=3xy-13xy平方=3×(

由2x²-3y²=xy得(X+Y)(2X-3Y)=0所以X=-y,或者2X=3Y,当X=-y时,代入得=-5当2X=3Y,代入得=15/14

答案是3/2你是不是把分母打错了教你个方法因为上下是齐次的直接令x=3y=2带入就行

3x²+3xy=03x²=-3xy因为x不等于0所以x=-y所以x：y=1：-1

2(x+xy)-[(xy-3y)-x]-(-xy)=2x+2xy-xy+3y+x+xy=3x+3y+2xy=3（x+y）+2xy=3*（-2）+2*3=0

y-x-2xy=0所以x-y=-2xyy-x=2xy所以原式=[3(x-y)+xy]\[(y-x)-xy]=[3×(-2xy)+xy]\(2xy-xy)=-5xy\xy=-5

x²-10x+25+|y-3|=0(x-5)²+|y-3|=0所以x=5,y=3代入计算即可

(3x^2+2xy)/xy-(2x^2-xy)/xy=(3x^2+2xy-2x^2+xy)/xy=(x^2+3xy)/xy=x(x+3y)/xy=(x+3y)/y

∵x-y=4xy，∴2x+3xy-2yx-2xy-y=2(x-y)+3xyx-y-2xy=8xy+3xy4xy-2xy=112．故答案为：112．

x+y=5xy（2x-3xy+2y)/(x+2xy+y）=[2（x+y）-3xy]/[(x+y)+2xy]=(2×5xy-3xy)/(5xy+2xy)=7xy/7xy=1再问：若x＋1/x＝3,求(x

1.第一题写得不清楚,根号里的表达式到底是怎么样的都不知道?2.a=3b=(√15)-3(b-√15）a-1=-3的平方=9

2x-3√(xy)-2y=0(2√x+√y)(√x-2√y)=0因为x>0,xy≥0所以y≥02√x+√y>0所以√x-2√y=0,即x=4y(x^2+4xy-16y^2)/(x^2+xy-9y^2)

∵x-y=4xy∴原式=[2(x-y)+3xy]/[-(x-y)-2xy]=(8xy+3xy)/(-4xy-2xy)=11xy/(-6xy)=-11/6