初一数学.因式分解那块的题目

计算

(x²y+xy²)÷(x+y)                    (4a²-12ab+9b²)÷(3b-2a)

 

(4x²-6x²y)÷(2-3y)              [(x+3y)²-4x²]÷(x+y)

解方程

81x²-4=0            (x-2)²=4x-8

 

 

已知x-y=3,xy=2,求x³y-2x²y²+xy³

 

 

 

 

要过程 答案

1.(x²y+xy²)÷(x+y)

=xy(y+x))÷(x+y)

=xy

2. (4a²-12ab+9b²)÷(3b-2a)

=(2a-3b)²÷(3b-2a)

=-(2a-3b)

3.(4x²-6x²y)÷(2-3y)

=2x²(2-3y)÷(2-3y)

= 2x²

4.[(x+3y)²-4x²]÷(x+y)

=(x+3y+2x)(x+3y-2x)÷(x+y)

=3(x+y)(3y-x)÷(x+y)

= 3(3y-x)

5.81x²-4=0

(9x+2)(9x-2)=0

x1=-2/9，x2=2/9

6.(x-2)²=4x-8

(x-2)²-4(x-2)=0

(x-2)(x-2-4)=0

x1=2，x2=6

7. x³y-2x²y²+xy³

=xy(x²-2xy+y²)

=xy(x-y)²

=2×3²

=18

你是一个懒惰而聪明家伙

1.=xy(x+y)÷(x+y)=xy    2.=[(2a)²-12ab+(2b)²]÷(3b-2a)=(2a-3b)²÷(3b-2a)=3b-2a

3.=2x²(2-3y)÷(2-3y)=2x²    4.=(x+3y-2x)(x+3y+2x)÷(x+y)=3(3y-x)(x+y)÷(x+y)=9y-3x

解方程

1.    (9x-2)(9x+2)=0    x=2/9,x=-2/9    2.(x-2)²-4(x-2)=0    (x-2-4)(x-2)=0    (x-6)(x-2)=0    x=6,x=2

3.=xy(x²-2xy+y²)

   =xy(x-y)²

   =18

(x^2y+xy^2)/(x+y)=xy(x+y)/(x+y)=xy (4a^2-12ab+9b^2)/(3b-2a)=(2a-3b)^2/(3b-2a)=(3b-2a)^2/(3b-2a)=3b-2a (4x^2-6x^2y)/(2-3y)=2x^2(2-3y)/(2-3y)=2x^2 [(x+3y)^2-4x^2]/(x+y)=[x^2+6xy+9y^2-4x^2]/(x+y)=-3[x^2-2x-3y^2]/(x+y)=-3(x+y)(x-3y)/(x+y)=-3x+9y 81x^2-4=0 81x^2=4 x^2=4/81 x=2/9或x=-(2/9) (x-2)^2=4x-8 x^2-4x+4=4x-8 x^2-4x+4-4x+8=0 x^2-8x+12=0 (x-2)(x-6)=0 x=2或x=6 x^3y-2x^2y^2+xy^3=xy*x^2-2(xy)^2+xy*y^2=2x^2-8+2y^2=2(x^2+y^2)-8=2(x-y)^2+2xy-8=2*9+4-8=14.

xy    3b-2a

2x²   5y+x

  +2/9或-9/2    -2或-6

xy（x-y）²

=18

解：计算

  (x²y+xy²)÷(x+y)

=xy(x+y)÷(x+y)

=xy

  (4a²-12ab+9b²)÷(3b-2a)

=-(2a-3b)²÷(2a-3b)

=-(2a-3b)

=3b-2a

  (4x²-6x²y)÷(2-3y)

=2x²(2-3y)÷(2-3y)

=2x²

  [(x+3y)²-4x²]÷(x+y)

=(x+3y+2x)(x+3y-2x)÷(x+y)

=3(x+y)(3y-x)÷(x+y)

= 3(3y-x)

解方程

    81x²-4=0

(9x+2)(9x-2)=0

∴9x+2=0或9x-2=0

∴x1=-2/9，x2=2/9

∴原方程的解是x1=-2/9，x2=2/9

    (x-2)²=4x-8

   x²-4x+4=4x-8

 x²-8x+12=0

(x-2)(x-6)=0

∴x-2=0或x-6=0

∴x1=2，x2=6

∴原方程的解是x1=2，x2=6

  x³y-2x²y²+xy³

=xy(x²-2xy+y²)

=xy(x-y)²

=2×3²

=18

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