\(5x^2-10xy+5y^2-20x^z=5\left(x^2-2xy+y^2-4z^2\right)=5\left[\left(x-y\right)^2-\left(2z\right)^2\right]=5\left(x-y-2z\right)\left(x-y+2x\right)\)

5x² - 10xy + 5y² - 20z = (5x² + 5y²) - (10xy + 20z)

                                  = 5 (x² + y²) - 10 (xy + 2z)

                                  = 5 [(x² + y²) - 2 (xy + 2z)] 

                                  = 5 [(x² + y²) - 2xy - 4z]

                                  = -5 (4z - y² + 2xy - x²)

5x² - 10xy + 5y² - 20z² 

= 5(x² - 2xy + y² - 4z²)

=  5[(x² - 2xy + y²) - 4z²]

= 5 [(x - y)² - (2z)²]

= 5 (x - y - 2z) (x - y +2z)

5x²-10xy+5y²-20z²

=5(x²-2xy+y²-4z²)

=5[(x-y)²-4z²]

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

dễ hiểu thôi.hơi vắn tắt 

a: \(x^4+2x^3+x^2=x^2\left(x+1\right)^2\)

b: \(5x^2+5xy-x-y\)

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

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

5x² - 10xy + 5y² - 20z²

=5(x² - 2xy + y² - 4z²)

= 5[ (x² - 2xy + y²) - (2z)²]

= 5[(x-y)² - (2z)²]

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

5x²-10xy+5y²-20z²

=5(x²-2xy+y²-4z²)

=5[(x-y)²-(2z)²]

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

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

=x^2(x+1)^2

b: =x^3+3x^2y+3xy^2+y^3-x-y

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

=(x+y)[(x+y)^2-1]

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

c: =5(x^2-2xy+y^2-4z^2)

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