Đáp án:
`g, -y^2 + 2xy - x^2 + 3x - 3y`
`= -(x^2 - 2xy + y^2) + (3x - 3y)`
`= -(x - y)^2 + 3(x - y)`
`= (x - y)[-(x - y) + 3]`
`= (x - y)(-x + y + 3)`
`h, x^3 - 2x^2 - x + 2`
`= (x^3 - 2x^2) - (x - 2)`
`= x^2 (x - 2) - (x - 2)`
`= (x - 2)(x^2 - 1)`
`= (x - 2)(x^2 - 1^2)`
`= (x - 2)(x - 1)(x + 1)`
`k, (a - b)(a + 2b) - (b - a)(2a - b) - (a - b)(a + 3b)`
`= (a - b)(a + 2b) + (a - b)(2a - b) - (a - b)(a + 3b)`
`= (a - b)[a + 2b + 2a - b - (a + 3b)]`
`= (a - b)(a +2b + 2a - b - a - 3b)`
`= (a - b)(2a - 2b)`
`= (a - b)(a - b).2`
`= 2(a - b)^2`
`m, (x + y)(2x - y) + (2x - y)(3x - y) - (y - 2x)`
`= (x + y)(2x - y) + (2x - y)(3x - y) + (2x - y)`
`= (2x - y)(x + y + 3x - y + 1)`
`= (2x - y)(4x + 1)`
