代数式10 |x 3| (2x y)的平方
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∵2x+y=0,∴4x3+2xy(x+y)+y3=2x[2x2+y(x+y)]+y3=2x[x(2x+y)+y2]+y3=2xy2+y3=y2(2x+y)=0.故答案为:0.
(3xy+10y)+5x-(2xy+2y-3x)=3xy+10y+5x-2xy-2y+3x=xy+8x+8y=-2+8(x+y)=-2+24=22
x³+2x²-4x+2010=x(x²+2x-4)+2010=0+2010=2010
x³-2x²-4x-5=(x³-2x²+x)-(5x-5)-10=x(x-1)²-5(x-1)-10将x=1+√5代入原式=(1+√5)(1+√5-1
∵x2-x-1=0,∴x3-2x+1=x(x2-x-1)+(x2-x-1)+2=0+0+2=2.
(3xy+10y)+[5x-(2xy+2y-3x)]=3xy+10y+5x-2xy-2y+3x=3xy-2xy+10y-2y+5x+3x=(3xy-2xy)+(10y-2y)+(5x+3x)=xy+8
24(3xy+10y)+[4x-2(3xy+2y-x)]=3xy+10y+4x-6xy-4y+2x=6x+6y-3xy=6(x+y)-3xy=6*3-3*(-2)=18+6=24
x的平方+X+1=0方程式不成立
原式=-x³+x²-x²+2x+2009=-x(x²-x)-x²+2x+2009=-x²+x+2009=2008
x3+3xy+y3=(x+y)(x2-xy+y2)+3xy,=(x2-xy+y2)+3xy,=(x+y)2-3xy+3xy,=1.
(3xy+2)^2+|7-x-y|=0,则3xy+2=0,7-x-y=0,即x+y=7,xy=-2/3(5xy+10y)-[-5x-(4xy-2y+3x)]=5xy+10y-(-5x-4xy+2y-3
(3xy+10y)+{5x-(2xy+2y-3x)}=3xy+10y+5x-2xy-2y+3x=xy+8x+8y=xy+8(x+y)xy=-2x+y=3xy+8(x+y)=-2+8×3=22
x²-x-1=0x²=x+1x³=x×x²=x(x+1)=x²+x=(x+1)+x=2x+1原式=-(2x+1)+2(x+1)+2002=-2x-1+
由x2+x-1=0得x2+x=1,∴x3+2x2-7=x3+x2+x2-7,=x(x2+x)+x2-7,=x+x2-7,=1-7,=-6.故选C.
2xy-x^2-y^2=-(x^2-2xy+y^2)=-(x-y)^2
x^3+2x^2-7=x(1-x)+2x^2-7=x+x^2-7=1-7=-6
(2x-y)分之5xy与10xy分之(2x-y)的乘积为0.5,前者等于2,后者等于0.25代数式6x-3?没写完?
用比差法.(3x3-2x2-4x+1)-(3x3+4x+10)=-2x2-8x-9=-2(x2+4x)-9=-2[(x+2)2-4]-9=-2(x+2)2-1<0即(3x3-2x2-4x+1)-(3x
这类题,先化简代数式为XY与X+Y的代数式,然后代入已知条件,就可以算出来.(3xy+10y)+[5x-(2xy+2y-3x)]=3XY+10Y+5X-2XY-2Y+3X=XY+8Y+8X=XY+8(