Bài 1:

a) \(7x^2\left(x^2-5x+1\right)=7x^4-35x^3+7x^2\)

b) \(\left(2x-3\right)\left(x+7\right)=2x^2+11x-21\)

Bài 2:

a) \(4x^2y-8x^3y^2=4x^2y\left(1-2xy\right)\)

b) \(2x-4y-ax+2ay=x\left(2-a\right)-2y\left(2-a\right)=\left(2-a\right)\left(x-2y\right)\)

\(ax+bx+ay+by\)

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

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

\(xy+1-x-y\)

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

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

\(x^2-y^2-5x-5y\)

\(=\left(x+y\right)\left(x-y\right)-5\left(x+y\right)\)

\(=\left(x+y\right)\left(x-y-5\right)\)

a) ax - 2x - a² + 2a

= ( ax - 2x ) - ( a² - 2a )

= x ( a - 2 ) - a ( a - 2 )

= ( a - 2 ) ( x - a )

b) x² + x - ax - a

= ( x² + x ) - ( ax + a )

= x ( x + 1 ) - a ( x + 1 )

= ( x + 1 ) ( x - a )

Hok Tốt!!!

a) ax -2x- a²+ 2a

= (ax -2x ) -(a² -2a )

= x(a-2) -a ( a-2 )

= (x-a) (a-2)

b) x² +x -ax -a

=( x² +x ) - ( ax +a )

= x( x+1 ) -a ( x+1 )

= ( x-a ) (x+ 1)

c) 2x² +4ax +x +2a

=( 2x² + 4ax )  + ( x+ 2a )

= 2x ( x+ 2a ) + ( x+2a )

= ( 2x +1 ) (x+2a )

d) 2xy -ax +x² - 2ay

= (2xy -2ay ) + (  -ax + x² )

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

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

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

\(=x\left(a-2\right)-a\left(a-2\right)=\left(x-a\right)\left(a-2\right)\)

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

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

c) \(2x^2+4ax+x+2a=\left(2x^2+x\right)+\left(4ax+2a\right)\)

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

d)  \(2xy-ax+x^2-2ay=\left(2xy-2ay\right)+\left(x^2-ax\right)\)

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

Hok tốt

= (a-y)² - 4²

= (a-y-4)(a-y+4)

\(x^2+ax+b\)

\(=\left(x^2+\frac{2ax}{2}+\frac{a^2}{4}\right)+b-\frac{a^2}{4}\)

\(=\left(x+\frac{a}{2}\right)^2-\left(\frac{a^2}{4}-b\right)\)

Với điều kiện: \(\frac{a^2}{4}-b\ge0\)thì phân tích được

\(=\left(x+\frac{a}{2}+\sqrt{\frac{a^2}{4}-b}\right)\left(x+\frac{a}{2}-\sqrt{\frac{a^2}{4}-b}\right)\)

\(1,x^2-16y^2=\left(x-4y\right)\left(x+4y\right)\)

\(2,21x-21y+ax-ay=21\left(x-y\right)+a\left(x-y\right)=\left(21+a\right)\left(x-y\right)\)

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

a) \(2a-4b=2\left(a-2b\right)\)

c) \(2ax-2ay+2a=2a\left(x-y+1\right)\)

e) \(3xy\left(x-4\right)-9x\left(4-x\right)=3x\left(x-4\right)\left(y+3\right)\)

b,d xem lại đề

b,d đúng mag bk