x+y=xy

|x|/x+y/|y|+xy/|xy|=由题可知x,y都不等于0.下面分x>0,y>0x>0yx0x四种情况去绝对值,这样就得到你要的答案啦.我复制楼下的结果来的,这是正确的.当x>0；y>0时,|x|/x+y/|y|+xy/|xy|=1+

证明|xy|=|x||y|这个是显而易见的.（1）x,y同号xy>0|x||y|=xy=|xy|(2)x,y|x||y|=-xy=|xy|∴|xy|=|x||y|

xy-(x+y)=1000xy-x-y+1=1001(x-1)(y-1)=1001=7*11*13xy-(x+y)=1000xy-x-y=1000x(y-1)-(y-1)-1=1000(x-1)(y-1)=1001二元二次方程有无数组解。其

证明|xy|=|x||y|证明：（1）x,y同号时,xy>0|x||y|=xy=|xy|(2)x,y异号时,xy0|x||y|=-xy=|xy|∴|xy|=|x||y|（1）x,y同号xy>0|x||y|=xy=|xy|(2)x,y|x||

计算：(根号xy-xy/x+根号xy)÷根号xy-y/x-y=看不懂你的题,应该和此题一样.见：http://zhidao.baidu.com/question/107327474.html?si=1

化简:(x+y-4xy/x+y)*(x-y-4xy/x-y)=题目是不是打错了一个符号.应该是：（x+y-4xy/(x+y))·（x-y+4xy/(x-y)）=[(x+y)²-4xy]/(x+y)·[(x-y)²+4xy

y'-xy=x/y通解原方程化为yy'-xy^2=x即2yy'-2xy^2=2x所以(y^2)'-2xy^2=2x设p=y^2所以p'-2xp=2x那么p=e^(∫2xdx)[∫2xe^(∫-2xdx)dx+C]=Ce^(x^2)-1所以y

xy"=y'ln(y'/x)令z=y',xz'=zln(z/x);令s=z/x,z=sx,x(s+xs')=sxln(s);s+xs'=sln(s);令t=ln(s),s=e^t;e^t+xe^tt'=e^tt;1+xt'=t;t'+xt'

sin(xy)=x求dx/dysec(xy)-y]/x还是x/[sec(xy)-y]x/[sec(xy)-y]dx/dy.dsin(xy)=dxcos(xy)d(xy)=dxcos(xy)(xdy+ydx)=dxxcos(xy)dy+yco

（-3x^y+2xy)-()=4x^+xy(-3x^y+2xy)-(4x^+xy)=-3x^y+2xy-4x^-xy=-3x^y+xy-4x^所以填上-3x^y+xy-4x^等比a3²=a1a4(a1+2d)²=a1(a

（xy-x的平方）*x-y分之xy=您好：（xy-x的平方）*x-y分之xy=x(y-x)*xy/(x-y)=-x²y如果本题有什么不明白可以追问,如果满意请点击“采纳为满意回答”如果有其他问题请采纳本题后另发点击向我求助,答题不

(xy-x平方)乘以x-y份之xy=?(xy-x平方)乘以x-y份之xy=x(y-x)*xy/(x-y)=-x²y如果本题有什么不明白可以追问,

(XY-X^2)除以X-Y/XY=?-X平方Y

1/x-1/y=x,求5y+xy-5y/y-xy-x=?5y+xy-5y/y-xy-x（分子分母同时除以xy）=(5(1/x-1/y)+1)/((1/x-1/y)-1)1/x-1/y=x=(5x+1)/(x-1)条件1/x-1/y=x不知道

x*x+xy=3,xy+y*y=2,则x*x+2xy+y*y=________?5

已知XY.Y=-3,求-XY(X.X.X.Y.Y.Y.Y.Y.Y.Y-3.X.X.Y.Y.Y.Y.Y-Y)的值.（过程完整）=-(xy^2)^4+3(xy^2)^3+(xy^2)^2=-27-27-3=-57xy^2=-3-XY(X.X.X

已知x+y=1,xy=-2,则x²y+xy²-2xyx²y+xy²-2xy=xy(x+y-2)=-2*(1-2)=2

已知x-xy=8,xy-y=-9,求x+y-2xy的值x-xy=8(1)xy-y=-9(2)则有(1)-(2):X-XY-XY+Y=X+Y-2XY=8-(-9)=17

1-2/x+y=xy,4y+6x=xy.求xy的解?1-(2/x)+y=4y+6x1-(2/x)=3y+6x(x-2)/x=3y+6xx-2=3xy+6x²x-2-6x²=3xyxy=(x-2-6x²)/3

已知xy>0,证明xy+xy/1+x/y+y/x>=4xy+1/xy>=2√（xy*1/xy）=2(当xy=1/xy即xy=1时取等号)x/y+y/x>=2√（x/y*y/x）=2(当x/y=y/x即x=y取等号)当x=y=1时可以同时满足