Câu 1 : x²-y²+2yz-z²=-(y²-2yz+z²-x²)                    Câu 2: x²-2xy+y²-xz+yz=(x²-2xy+y²)-xz+yz

                                 =-(y-z)² -x²                                                                   =(x-y)²-z(x-y)

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

ta có :

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

x² - z² + y² - 2xy

= (x² - 2xy + y² )- z²

= (x-y)² - z²

= (x-y-z)(x-y+z) 

x² - 2xy - 4z² + y²

= (x² - 2xy+y²) - (2z)²

= (x-y)²- (2z)²

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

x²-2xy-4z²+y²

=(x²-2xy+y²)-(2z)²

=(x-y)²-(2z)²

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

x^2 - 2xy - (4z)^2 + y^2

=(x-y)^2 - (4z)^2

= (x-y-4z)(x-y+4z)

Câu 1: 3x² - 6xy + 3y² - 12z²

= 3(x² - 2xy + y² - 4z²)

= 3[(x² -2xy+y²)- (2z)²]

= 3[(x-y)² - (2z)²]

=3(x-y-2z)(x-y +2z)

Câu 2: x² - 6xy - 25z²+ 9y²

= x² - 2x.3y + (3y)² - (5z)²

= (x-3y)² - (5z)²

= (x-3y-5z)(x-3y+5z) 

x²-y²-2xy+y²

=x²-2xy

=x(x-2y)

x² - y² - 2xy + y²

= (x² - 2xy +y²) - y²

= (x-y)² - y²

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

= x(x-2y)

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

tiểu học mà bảo toán lớp 8

bạn đã suy nghĩ chưa

x^9-x^7-x^6-x^5+x^4+x^3+x^2-1
=>x^8(x+1)-x^7(x+1)-x^5(x+1)+x^3(x+1)+(x+1)(x-1)
<=>(x^8-x^7-x^5+x^3+x-1)(x+1)