Đáp án:
Câu `1`
`a, 4x^2 - 6x`
`= 2x.2x - 2x.3`
`= 2x(2x - 3)`
`b, 9x^4 y^3 + 3x^2 y^4`
`= 3x^2 y^3 . 3x^2 + 3x^2 y^3 .y`
`= 3x^2 y^3 (3x^2 + y)`
`c, x^3 - 2x^2 + 5x`
`= x(x^2 - 2x + 5)`
`d, 3x(x - 1) + 5(x - 1)`
`= (x - 1)(3x + 5)`
`e, 2x^2(x + 1) + 4(x + 1)`
`= (x + 1)(2x^2 + 4)`
`= (x + 1)(x^2 + 2).2`
`f, - 3x - 6xy + 9xz`
`= -3x. 1 - 3x.2y + (-3x).(-3z)`
`= -3x(1 - 2y - 3z)`
`g, 2x^2 y - 4xy^2 + 6xy`
`= 2xy.x - 2xy.2y + 2xy.3`
`= 2xy(x - 2y + 3)`
`h, 4x^3 y^2 - 8x^2 y^3 + 2x^4 y`
`= 2x^2 y . 2xy - 2x^2 y.4y^2 + 2x^2 y.x^2`
`= 2x^2 y (2xy - 4y^2 + x^2)`
Câu `1`
`1, x^2 - 8x + 16`
`= x^2 - 2.x.4 + 4^2`
`= (x - 4)^2`
`2, x^2 - 36`
`= x^2 - 6^2`
`= (x - 6)(x + 6)`
`3, 9x^2 + 2x + 1/9`
`= (3x)^2 + 2.3x. 1/3 + (1/3)^2`
`= (3x + 1/3)^2`
`4, 4x^2 - 9`
`= (2x)^2 - 3^2`
`= (2x - 3)(2x + 3)`
`5, x^2 + 6x + 9`
`= x^2 + 2.x.3 + 3^2`
`= (x + 3)^2`
`6, 16x^2 - 8x + 1`
`= (4x)^2 - 2.4x.1 + 1^2`
`= (4x - 1)^2`
`7, 4x^2 - 49`
`= (2x)^2 - 7^2`
`= (2x - 7)(2x + 7)`
`1, x^3 + 8`
`= x^3 + 2^3 = (x + 2)(x^2 - 2x + 2^2)`
`= (x + 2)(x^2 - 2x + 4)`
`2, 27x^3 - 1`
`= (3x)^3 - 1^3`
`= (3x - 1)[(3x)^2 + 3x.1 + 1^2]`
`= (3x - 1)(9x^2 + 3x + 1)`
