a: \(=25x^2-4y^2+4y-1\)

\(=25x^2-\left(2y-1\right)^2\)

\(=\left(5x-2y+1\right)\left(5x+2y-1\right)\)

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

a, \(\left(5x-2y\right)\left(5x+2y\right)+4y-1=25x^2-4y^2+4y-1\)

\(=\left(5x\right)^2-\left(4y^2-4y+1\right)=\left(5x\right)^2-\left(2y-1\right)^2=\left(5x-2y+1\right)\left(5x+2y-1\right)\)

b, t đag loading :)) phải vận dụng kiến thức đầu có nhóm zô, tí giải choa nhá :) 

Okie :)))

a. ( 5x - 2y ) ( 5x + 2y ) + 4y - 1

= 25x² - 4y² + 4y - 1

= ( 5x )² - ( 2y - 1 )²

= ( 5x - 2y + 1 ) ( 5x + 2y - 1 )

b. x² ( xy + 1 ) + 2y - x - 3xy

= x³y + x² + 2y - x - 3xy

= ( x³y + x²y + x² - 2xy ) - ( x²y + xy + x - 2y )

= x ( x²y + xy + x - 2y ) - ( x²y + xy + x - 2y )

= ( x - 1 ) ( x²y + xy + x - 2y )

a) \(14x^2y-21xy^2+28x^2y^2\)

\(=7xy\left(2x-3y+4xy\right)\)

b) \(3x^2-5x-3xy+5y\)

\(=\left(3x^2-3xy\right)-\left(5x-5y\right)\)

\(=3x\left(x-y\right)-5\left(x-y\right)\)

\(=\left(x-y\right)\left(3x-5\right)\)

c) \(5a^3-20a\)

\(=5a\left(a^2-4\right)\)

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

d) \(2x+2y+x^2+2xy+y^2\)

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

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

a: \(=\dfrac{2}{5}\left(xy-x-y^2+1\right)\)

\(=\dfrac{2}{5}\left[x\left(y-1\right)-\left(y-1\right)\left(y+1\right)\right]\)

\(=\dfrac{2}{5}\left(y-1\right)\left(x-y-1\right)\)

b: \(=x\left(x^2+2xy+y^2-9\right)\)

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

=25(y−1)(x−y−1)=25(y−1)(x−y−1)

b) $=x\left({}^{}+2xy+{}^{}-9\right)$

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

a) \(14x^2y-21xy^2+28x^2y^2=7xy\left(2x-3y+4xy\right)\)

b) \(3x^2-3xy-5x+5y=3x\left(x-y\right)-5\left(x-y\right)=\left(3x+5\right)\left(x-y\right)\)