1. 2x(3x² - 5x + 3) = 6x³ - 10x² + 6x

2. \(-\dfrac{1}{2}x^2\left(2x^3-4x+3\right)=-x^5+2x^3+\dfrac{-3}{2}x^2\)

3. -2x(x² + 5x - 3) = -2x³ - 10x² + 6x

4. x(3x² - 2x + 5) = 3x³ - 2x² + 5x

5. 3xy²(2x - 4y + 3xy) = 6x²y² - 12xy³ = 9x²y³

[(x²-2xy+2xy²).(x+2y)-(x²+4y²).(x-y)]2xy

=( x³ + 2x²y-2x²y-4xy²+2x²y²+4xy³-x³+x²y-4xy²+4y³ )2xy

=2xy(2x²y²-8xy²+4xy³+x²y+4y³)

= 4x³y³-16x²y³+8x²y⁴+2x³y²+8xy⁴

Trả lời:

[ ( x² - 2xy + 2xy² ) ( x + 2y ) - ( x² + 4y² ) ( x - y ) ] 2xy

= [ ( x³ + 2x²y - 2x²y - 4xy² + 2x²y² + 4xy³ ) - ( x³ - x²y + 4xy² - 4y³ ) ] 2xy

= ( x³ + 2x²y - 2x²y - 4xy² + 2x²y² + 4xy³ - x³ + x²y - 4xy² + 4y³ ) 2xy

= ( x²y - 8xy² + 2x²y² + 4xy³ + 4y³ ) 2xy

= 2x³y² - 16x²y³ + 4x³y³ + 8x²y⁴ + 8xy⁴

a: \(=\left(x-y\right)\left(x^2+2\right)\)

           Bài làm :

 \(\text{a)}9\left(x+y-1\right)^2-4\left(2x+3y+1\right)^2\)

\(=\left(3x+3y-3\right)^2-\left(4x+6y+2\right)^2\)

\(=\left(3x+3y-3-4x-6y-2\right)\left(3x+3y-3+4x+6y+2\right)\)

\(=\left(-x-3y-5\right)\left(7x+9y-1\right)\)

 \(\text{b)}3x^4y^2+3x^3y^2+3xy^2+3y^2\)

\(=\left(3x^4y^2+3xy^2\right)+\left(3x^3y^2+3y^2\right)\)

\(=3xy^2\left(x^3+1\right)+3y^2\left(x^3+1\right)\)

\(=\left(3xy^2+3y^2\right)\left(x^3+1\right)\)

\(=3y^2\left(x+1\right)\left(x+1\right)\left(x^2-x+1\right)\)

\(=3y^2\left(x+1\right)^2\left(x^2-x+1\right)\)

 \(\text{c)}\left(x+y\right)^3-1-3xy\left(x+y-1\right)\)

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

\(=\left(x+y-1\right)\left(x^2+2xy+y^2+x+y+1-3xy\right)\)

\(=\left(x+y-1\right)\left(x^2+x+y^2+y+1-xy\right)\)

\(d ) x^3+3x^2+3x+1-27z^3\)

\(=\left(x+1\right)^3-\left(3z\right)^3\)

\(=\left(x+1-3z\right)\left(x^2+2x+1+3xz+3z+9z^2\right)\)

Bài 2: 

a: \(3x^2-3xy=3x\left(x-y\right)\)

b: \(x^2-4y^2=\left(x-2y\right)\left(x+2y\right)\)

c: \(3x-3y+xy-y^2=\left(x-y\right)\left(3+y\right)\)

d: \(x^2-y^2+2y-1=\left(x-y+1\right)\left(x+y-1\right)\)

ỳtct7ct7c7c7t79tc9

đa thức lớp 5 hả bạm

đa thức lớp 5 à

mình ghi sao đề, các bạn ko cần làm đâu

Bài làm

1.

a) 5x.3xy² 

= 15x²y² 

b) ( -2/3 xy²z )( -3x²y)² 

= ( -2/3xy²z)( 9x⁴y² )

= -6x⁵y⁴z

2)

a) M = P + Q = ( 3x²y - 2x + 5xy² - 7y² ) + ( 3xy² - 7y² - 9x²y - x - 5 )

                  = 3x²y - 2x + 5xy² - 7y² + 3xy² - 7y² - 9x²y - x - 5 

                  = ( 3x²y - 9x²y ) + ( 5xy² + 3xy² ) + ( -2x - x ) + ( -7y² - 7y² ) - 5

                  = -6x²y + 8xy² - 3x -14y² - 5

Vậy M = P + Q = -6x²y + 8xy² - 3x -14y² - 5

b) M = Q - P = ( 3xy² - 7y² - 9x²y - x - 5 ) - ( 3x²y - 2x + 5xy² - 7y² ) 

                   = 3xy² - 7y² - 9x²y - x - 5 - 3x²y + 2x - 5xy² + 7y²         

                   = ( -3x²y - 9x²y ) + ( 3xy² - 5xy² ) + ( 2x - x ) + ( -7y² + 7y² ) - 5

                  = -11x²y - 2xy² + x - 5

Vậy M = Q - P = -11x²y - 2xy² + x - 5

a) \(9\left(x+y-1\right)^2-4\left(2x+3y+1\right)^2\)

\(=\left(3x+3y-3\right)^2-\left(4x+6y+2\right)^2\)

\(=\left(3x+3y-3-4x-6y-2\right)\left(3x+3y-3+4x+6y+2\right)\)

\(=\left(-x-3y-5\right)\left(7x+9y-1\right)\)

b) \(3x^4y^2+3x^3y^2+3xy^2+3y^2\)

\(=\left(3x^4y^2+3xy^2\right)+\left(3x^3y^2+3y^2\right)\)

\(=3xy^2\left(x^3+1\right)+3y^2\left(x^3+1\right)\)

\(=\left(3xy^2+3y^2\right)\left(x^3+1\right)\)

\(=3y^2\left(x+1\right)\left(x+1\right)\left(x^2-x+1\right)\)

\(=3y^2\left(x+1\right)^2\left(x^2-x+1\right)\)

c) \(\left(x+y\right)^3-1-3xy\left(x+y-1\right)\)

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

\(=\left(x+y-1\right)\left(x^2+2xy+y^2+x+y+1-3xy\right)\)

\(=\left(x+y-1\right)\left(x^2+x+y^2+y+1-xy\right)\)