与"已知x y=负2,xy=3.试求:2{xy加{负3}减3x加2y"相等的题-搜答案-搜搜做题作业网

将一式变形可得（x方-y方）/xy=1x方y负方等于1加x/y（左右同除y方即可）y方x负方等于1减y/x（同理）将其带入二式中可得2+x/y-y/x通分得2加（x方-y方）/xy所以等于3

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

A=2X²+3XY+2X-1,B=-X²+XY-1∵3A+6B=3(2X²+3XY+2X-1)+6(-X²+XY-1)=9XY+6X-3+6XY-6=15XY+

原式=2xy-6x-6y+3xy=5xy-6(x+y)=5×3-6×(-2)=27

-xy（x^2y^5-xy^3-y)=-(xy^2)^3+(xy^2)^2+xy^2=-(-2)^3+4-2=8+4-2=10

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×(

x^2-y^2=xy两边同除以xy得：x/y-y/x=1xy^-1-x^-1y=1再问：解分式方程（1）7/2+(900-3x/1.2x)=900/x(2)(100/2a)+1/2=(300/2a)+

（1）∵xy+x=-1①，xy-y=-2②，∴①-②得x+y=1；（2）先把xy+x=-1，xy-y=-2的值代入代数式，得原式=-x-[2y-1+3x]+2[x+4]=-x-2y+1-3x+2x+8

已知A=2X的2次方+3XY+2X-1,B=负X的平方+XY=3x,且a-2B的值与X无关,求Y的值A-2B=XY+8X-1值与X无关,得Y=-8

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

xx+2xy-yy=-3两式相加即可

由A=5x*2y-3xy*2+4xy,B=7xy*2-2xy+x*2y得,A+B=6x*2y+4xy*2+2xy则,所求的式子可转化为-0.5x(6x*2y+4xy*2+2xy)-5x*2y-3xy*

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

x+y=3xyx^4+y^4+2(xy)^2=9(xy)^2x^4+y^4=7x^2y^2xy的负二次方+x的负二次方y=x^2/y^2+y^2/x^2=x^4+y^4/x^2y^2=7

依题意知：（x-1）（y+1）=-1,化解得：xy+x-y-1=-1,x-y=-xy,两边同时除以xy得：1/y-1/x=-1

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

3xy=2x+3y+5(3y-2)(x-1)=7所以3y-2=7x-1=1得y=3x=2xy=6或3y-2=1x-1=7得y=1x=6xy=6所以xy=6

=xy(1-2y^2)=-0.119616

原式=-xy²（x²y^4-xy²-1）∵xy²=-2原式=2（（-2)²-（-2）-1）=10