代数式10-|x 3|-(2x y)的平方有最大值或最小值吗?-搜答案-智慧作业帮

∵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

因为A+B+C=x3-2y3+3x2y+xy2-3xy+4+y3-x3-4x2y-3xy-3xy2+3+y3+x2y+2xy2+6xy-6=1，所以，对于x、y、z的任何值A+B+C是常数．

(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

x3+3xy+y3=（x+y）（x2-xy+y2）+3xy，=（x2-xy+y2）+3xy，=（x+y）2-3xy+3xy，=1．

5xy/(2x-y)=2所以10xy/(2x-y)=4所以(2x-y)/(10xy)=1/415xy/(6x-3)=3×5xy/[3(2x-y)]=5xy/(2x-y)=2

|X1-1|+|X2-2|+|X3-3|+...+|X2005-2005|=0所以|X1-1|=0,|X2-2|=0,|X3-3|=0,...,|X2005-2005|=0即x1=1,x2=2,x3=

(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

要求的式子=(x³－y³)＋(3xy²－x²y）－2（x²y－y³）=x³－y³＋3xy²－x²y－

2xy-x^2-y^2=-(x^2-2xy+y^2)=-(x-y)^2

（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?

x3+（y-1）x2-2xy-y2=x^3+x^2y-x^2-2xy-y^2=x^2(x+y)-(x+y)^2=(x+y)(x^2-x-y)

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(

x^3+x^2+xy-xy^2=x(x^2+x+y-y^2)=x(x^2-y^2+x+y)=x[(x+y)(x-y)+(x+y)]=x(x+y)(x-y+1)