Đáp án+Giải thích các bước giải:
`a) (3x - 1)² - 16`
`= (3x - 1 - 4)(3x - 1 + 4)`
`= (3x - 5)(3x + 3)`
`b) (5x - 4)² - 49x²`
`= (5x - 4 - 7x)(5x - 4 + 7x)`
`= (-2x - 4)(12x - 4)`
`= - 8(x + 2)(3x - 1)`
`c) (2x + 5)² - (x - 9)²`
`= (2x + 5 - x + 9)(2x + 5 + x - 9)`
`= (x + 14)(3x - 4)`
`d) (3x + 1)² - 4(x - 2)²`
`= (3x + 1 - 2x + 4)(3x + 1 + 2x - 4)`
`= (x + 5)(5x - 3)`
`e) 9(2x + 3)² - 4(x + 1)²`
`= (6x + 9 - 2x - 2)(6x + 9 + 2x + 2)`
`= (4x + 7)(8x + 11)`
