`1, x^2-2x-4y^2-4y`
`=(x^2-4y^2)-(2x+4y)`
`=(x-2y)(x+2y)-2(x+2y)`
`=(x+2y)(x-2y-2)`
`2, 3a^2-6ab+3b^2-120`
`-> \text{Sửa đề:}3a^2-6ab+3b^2-12`
`=3(a^2-2ab+b^2-4)`
`=3[(a-b)^2-2^2]`
`=3(a-b-2)(a-b+2)`
`3, x^2(x-1)+16(1-x)`
`=x^2(x-1)-16(x-1)`
`=(x-1)(x^2-16)`
`=(x-1)(x-4)(x+4)`
`4, a^2+2ab+b^2-ac-be`
`-> \text{Sửa đề:} a^2+2ab+b^2-ac-bc`
`=(a+b)^2-c(a+b)`
`=(a+b)(a+b-c)`
`5, xz-yz-x^2+2xy-y^2`
`=z(x-y)-(x^2-2xy+y^2)`
`=z(x-y)-(x-y)^2`
`=(x-y)(z-x+y)`
`6, 2x+2y-x^2-xy`
`=2(x+y)-x(x+y)`
`=(x+y)(2-x)`