已知x y=3,x² y²=7
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已知x/y=7/2,(2x²+3xy+2y²)/(x²+2xy+y²)=(2x/y+3+2y/x)/(x/y+2+y/x)=(2×7/2+3+2×2/7)/(7
(x^2-3XY+2Y^2)/(X^2-2XY+Y^2)=(x-2y)(x-y)/(x-y)^2=(x-2y)/(x-y)=(x-y-y)/(x-y)=1-y/(x-y)=1-1/(x/y-1)=1-
1、因为(X+Y)的平方=X的平方+Y的平方+2XY,所以X的平方+Y的平方=(X+Y)的平方-2XY=9-(-7)=9+7=162、因为(X+Y)的平方=X的平方+Y的平方+2XY,所以X的平方-X
xy^2=-6(xy^2)^2=(-6)^2即x^2y^4=36(xy^2)^3=(-6)^3即x^3y^6=-216-xy(x^3y^7-3x^2y^5-y)=-xy[(x^3y^6)*y-3(x^
已知xy^2=-2那么-xy(x^3y^7-3x^2y^5-y)=-x^4y^8+3x^3y^6+xy^2=-(-2)^4+3*(-2)^3+(-2)=-16-24-2=-42如果不懂,请Hi我,祝学
楼主算得对,第一个回答在第二步的地方把三次方的系数3弄丢掉了,所以正确的还是-165
-xy(x^2y^5-xy^3-y)=-(xy^2)^3+(xy^2)^2+xy^2=-(-2)^3+4-2=8+4-2=10
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
先把代数式(5XY+4X+7Y)+(6X-3XY)-(4XY-3Y)化简(5XY+4X+7Y)+(6X-3XY)-(4XY-3Y)=5XY+4X+7Y+6X-3XY-4XY+3Y=-2XY+10X+1
xy(2x^3y^7+5x^2y^5-y)=xy[2y(xy^2)^3+5y(xy^2)^2-y]=xy[2y(-2)^3+5y(-2)^2-y]=xy(-16y+20y-y)=3xy^2=3*(-2
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.
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=4xy,∴2x+3xy-2yx-2xy-y=2(x-y)+3xyx-y-2xy=8xy+3xy4xy-2xy=112.故答案为:112.
因为x-y=-2xy所以将x-y都换成-2xy了
原式=x^4y^8-3x³y^6-11.5xy²=(xy²)^4-3(xy²)³-11.5(xy²)=1296+648+69=2013
因为,x-y=3xy所以:-3x+6xy+3y/[(7x-5y)-9xy-(3x-y)]=[-3(x-y)+6xy]/[(7x-5y)-9xy-(3x-y)]=[-3*3xy+6xy]/[7x-5y-
[(x-y)^2+2xy-y^2]/[x^2+7xy+y^2]=[x²-2xy+y²+2xy-y²]/[x^2+7xy+y^2]=x²/[x^2+7xy+y^2
原式=-xy²(x²y^4-xy²-1)∵xy²=-2原式=2((-2)²-(-2)-1)=10