已知x y=负7,xy=12求y根号y分之x-搜答案-大师作文网

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

(x^2+3xy+2y^2)/(x^2y+2xy^2)=(x+2y)(x+y)/[xy(x+2y)]=(x+y)/(xy)将x+y=7,xy=12代入(x+y)/(xy)=7/12

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

(4xy+12y)+(7x-(3xy+4Y-x))=4xy+12y+(7x-3xy-4y+x)=4xy+12y+7x-3xy-4y+x=(4-3)xy+(12-4)y+(7+1)x=xy+8y+8x当

原式=6x+4xy+2xy+3x+2y-4xy+7y=9x+9y+2xy=9(x+y)+2xy=9×4+2×2=36+4=40

5xy+4x+7y+6x-3xy-4xy+3y=5xy-3xy-4xy+4x+6x+7y+3y=（5-3-4）xy+（4+6）x+（7+3）y=-2xy+10x+10y=-2xy+10（x+y）因为x

x^2y+xy^2=xy（x+y）=7x6=42再问：��(x+1)^2=13��x^2+2x+3=再答：x^2+2x+3=（x+1）^2+2=13+2=15

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*

最简单的方法就是用特殊值,令x=-2,y=1然后代入所求表达式,求出其值.为-8；另外此内题的另一个解法是变化所求表达式,使它变成关于xy^2的表达式.

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

解-1/3x(xy²+y+x³y的4次方)=-1/3x[(xy)y+y+(xy)³×y]=-1/3x(y+y+y)=-1/3x*3y=-xy=-1

已知X,Y互为负倒数则xy=-1（a-5）*（a-5）+|b+5|-{（xy)*(xy)*(xy）}/5=(a-5)²+Ib+5I-(-1)/5=1/5即(a-5)²+Ib+5I=

[y+1/x+1]+[x+1/y+1]=(y+1)^2/(x+1)(y+1)+(x+1)^2/(x+1)(y+1)=[(Y+1)^2+(x+1)^2]/(x+1)(y+1)=[y^2+2y+1+x^2

x^2+xy=12,xy+y^2=15x/y=4/5y^2-x^2=3(y-x)(y+x)=3(x+y)=3/(y-x)（x+y)^2/（x-y)^4=9(x-y)^2=243

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

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x^2-7xy+12y=0,且x.y不等于0(x-3y)(x-4y)=0x=3y或x=4y(x^2-2xy+y^2)/(2xy)=(x-y)^2/(2xy)x=3y时原式=4y^2/(6y^2)=2/

x²-7xy+12y²=0(x-3y)(x-4y)=0x1=3yx2=4yx=3y时原式＝9y²-3y²+y²/6y²=7/6x=4y时原式

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