3x-2xy-8-2x 6xy-x2 6合并同类项-搜答案-神马作文网

：(2x-y)(x^2+xy-2y^2)=（2x-y）（x+2y)(x-y)xy(x^2-xy)(-3xy^2)=xy*x(x-y)*(-3xy^2)=-3x^3y^3(x-y)

解2(x²-xy)-3(2x²-3xy)=(2x²-6x²)+(-2xy+9xy)=-4x²+7xy再问：��|-15|-8�£�-2��+4*�

对.前提是x不等于y

3xy[2xy-x(y-2)+x-1]=3xy(2xy-xy+2x+x-1)=3xy(xy+3x-1)=3x^2y^2+9x^2y-3xy

3xy[2xy-x（y-2）+x]＝3xy[2xy-xy+2x+x]=3xy(xy+3x)=3x²y²+9x²y

(-3x^y+2xy)-(4x^+xy)=-3x^y+2xy-4x^-xy=-3x^y+xy-4x^所以填上-3x^y+xy-4x^

(8xy-3x平方)-5xy-2(3xy-2x平方)=8xy-3x²-5xy-6xy+4x²=x²-3xy=4+6=10

（x^2+3x+2)(3+8x+4x^2)-90=（x+2）（x+1）（2x+1）（2x+3）-90=（x+2）（2x+1）（x+1）（2x+3）-90=（2x^2+5x+2）(2x^2+5x+3)-

-4x²y-8xy²+2x²y-3xy²=-2x²y-11xy²=-xy(2x+11y)

1、已知2x²+xy=10,3y²+2xy=6,求4x²+8xy+9y²的值为?分析：通过观察,可以把8xy拆成2xy+6xy,分别于剩余的两项组合,并提取公因

-3(2x²-xy)+4(x²+xy-6)

-3(2x²-xy)+4(x²+xy-6)=6x²+3xy+4x²+4xy-24=-2x²+7xy-24

3x-2xy-8-2x+6xy-x²+6=-x²+(-2+6)xy+(3-2)x+(-8+6)=-x²+4xy+x-2-x²+2xy-y²-3x

2x²-3xy+(2xy-x²)=2x²-3xy+2xy-x²=x²-xy=x(x-y)

-3(2x^2-xy)+4(x^2+xy-6)

-3(2x^2-xy)+4(x^2+xy-6)=-6x^2+3xy+4x^2+4xy-24=-2x^2+7xy-24再问：thankyou~

原式=1-3xy+x+(-4x-6xy)=1-3xy+x-4x-6xy=1-3x-9xy

(3x^2+2xy)/xy-(2x^2-xy)/xy=(3x^2+2xy-2x^2+xy)/xy=(x^2+3xy)/xy=x(x+3y)/xy=(x+3y)/y

设X=kY.kY^2/(3k+2)Y=1/8kY^2/((2k+3)Y=1/7由上式得：3k+2=8kY,2k+3=7kY所以2/（8Y-3）=3/（7Y-2）所以Y=1/2,X=1

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

原式=-x²y+2xy²+2x²y²-4xy³-3x³+27x³y-18x²y²+2x²y-18x&

（1）-3X^-2XY-8XY-(-5Y^2)-2X^2-Y^2=-3x^2-2xy-8xy+5y^2-2x^2-y^2=-5x^2-10xy+4y^2（2）3(-2+3X-X^2)-(4-3X+X^