a ) ( x - 2 )( x + 5 )

= x^2 + 5x - 2x + 10

= x^2 + 3x + 10

b ) 3x + 3y +ax + ay 

= x( 3 + a ) + y( 3 + a )

= ( 3 + a )( x + y ) 

c ) ( x^2 + 2xy ) : ( x + 2y )

= [ x( x + 2y ) ] : ( x + 2y )

= x  : 1

= x 

d ) ( x - 2 )( x + 2 ) + ( x + 1 )^2 - 2x^2 = 0 

       x^2 + 2x - 2x - 4 + x^2 + x + x + 1 - 2x^2 = 0

       x^2 - 4 + x^2 + 2x + 1 - 2x^2 = 0

        2x^2 + 2x - 4 + 1 - 2x^2 = 0 

       2x - 3 = 0

       2x = 0 + 3

       2x = 3

        x = 3 : 2

        x = 3/2 

a)   \(\left(x-2\right)\left(x+5\right)\)

\(=x^2+5x-2x-10\)

\(=x^2+3x-10\)

b)  \(3x+3y+ax+ay\)

\(=3\left(x+y\right)+a\left(x+y\right)\)

\(=\left(x+y\right)\left(3+a\right)\)

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

\(=\left[x\left(x+2y\right)\right]:\left(x+2y\right)\)

\(=x\)

d)  \(\left(x-2\right)\left(x+2\right)+\left(x+1\right)^2-2x^2=0\)

\(\Leftrightarrow\)\(x^2-4+x^2+2x+1-2x^2=0\)

\(\Leftrightarrow\)\(2x-3=0\)

\(\Leftrightarrow\)\(2x=3\)

\(\Leftrightarrow\)\(x=\frac{3}{2}\)

Vậy....

(x-2)(x+5)=x^2+5x-2x-10=x^2+3x-10

3x+3y+2x+2y=3(x+y)+2(x+y)=5(x+y)

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

x^2-4+x^2+2x+1-2x^2=0 khi 2x-3=0 khi x=3/2

a) \(ax+ay-3x-3y=a\left(x+y\right)-3\left(x+y\right)=\left(a-3\right)\left(x+y\right)\)

b) \(x^3-3x^2+3x-9=x^2\left(x-3\right)+3\left(x-3\right)=\left(x-3\right)\left(x^2+3\right)\)

c) xem lại đề

d) \(9-x^2-2xy-y^2=9-\left(x+y\right)^2=\left(3-x-y\right)\left(3+x+y\right)\)

1.

7x(2x-1)=14x²-7x

2

a. x²+2x=x(x+2)

b.x²-xy+3x-3y

=x(x-y)+3(x-y)

=(x+3)(x-y)

Câu 2:

 1. 2x/2x-5 -  5/2x-5

=2x-5/2x-5

=1

2. (6x³-7x²-x+2) : (x-1)=6x²-x-2

a: =x(x-5)

a) \(=x\left(x-5\right)\)

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

c) \(=x\left(x+y\right)-3\left(x+y\right)=\left(x+y\right)\left(x-3\right)\)

b,=(x+3y-3y(x+3y+3y)

= x(x+6y)

\(a,3x^2+2x=x\left(3x+2\right)\)

\(b,5x-5y+ax-ay=5\left(x-y\right)+a\left(x-y\right)=\left(x-y\right)\left(5+a\right)\)

\(c,4x^2-25=\left(2x-5\right)\left(2x+5\right)\)

\(d,x^2+6x+5=x^2+x+5x+5=x\left(x+1\right)+5\left(x+1\right)=\left(x+1\right)\left(x+5\right)\)

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

a ) 3x² + 2x

= x. ( 3x + 2 )

b ) 5x - 5y + ax - ay

= ( 5x + ax ) - ( 5y + ay )

= x.( 5 + a ) - y ( 5 + a )

= ( 5 + a ) ( x - y ) 

c ) 4x² - 25

= ( 2x + 5 ) ( 2x - 5 )

d ) x² + 6x + 5

= x² + x + 5x + 5

= x.( x + 1 ) + 5.( x + 1 )

= ( x + 1 ) ( x + 5 )

e ) x² - y² + 2y - 1

= x² - ( y - 1 )²

= ( x - y + 1 ) ( x + y - 1 )

f ) x³ - 3x + 2

= x³ + 2x² - 2x² - 4x + x + 2

= x² ( x + 2 ) - 2x ( x + 2 ) + ( x + 2 )

= ( x + 2 ) ( x² - 2x + 1 )

= ( x + 2 ) ( x - 1 )²

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

\(b)\)\(5x-5y+ax-ay=5\left(x-y\right)+a\left(x-y\right)=\left(x-y\right)\left(a+5\right)\)

\(c)\)\(4x^2-25=\left(2x\right)^2-5^2=\left(2x-5\right)\left(2x+5\right)\)

\(d)\)\(x^2+6x+5=\left(x^2+x\right)+\left(5x+5\right)=x\left(x+1\right)+5\left(x+1\right)=\left(x+1\right)\left(x+5\right)\)

\(e)\)\(x^2-y^2+2y-1\)

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

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

\(=\)\(\left(x-y+1\right)\left(x+y-1\right)\)

\(f)\)\(x^3-3x+2\)

\(=\)\(\left(x^3-x\right)-\left(2x-2\right)\)

\(=\)\(x\left(x^2-1\right)-2\left(x-1\right)\)

\(=\)\(x\left(x-1\right)\left(x+1\right)-2\left(x-1\right)\)

\(=\)\(\left(x-1\right)\left[x\left(x+1\right)-2\right]\)

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

Chúc bạn học tốt ~ 

câu 2: c,4x^4 y^4

\(2,B\\ 3,D\\ 4,D\\ 5,B,C\\ 6,A\\ 7,C\\ 8,A\)

a: =(x+y)(x-3)

b: =x(x^2-2x+1+4y^2)

1: \(\dfrac{A}{B}=\dfrac{2x^4+4x^3-x^3-2x^2-2x^2-4x+x+2}{x+2}\)

\(=2x^3-x^2-2x+1\)

bài 1:

a) x(x-2)-5y-(x-2)=(x-5y)(x-2)

b) =(2x-3-4x)(2x-3+4x)=(-2x-3)(6x-3)

bài 2 bạn tự luyện nhé