Giải thích các bước giải:

`1B.`

`a) 2y - 6 = 2(y - 3)`

`b) 5x^2 - 10x^3 = 5x^2(1 - 2x)`

`c) 3x^4 - 27x^3 = 3x^3(x - 9)`

`d) -8x^3y - 16xy^3 = -8xy(x^2 + 2y^2)`

`2A.`

`a) 2x(x - 2) + 3(x - 2) = (2x + 3)(x - 2)`

`b) -3(2x + 1) + 5x(2x + 1) = (5x - 3)(2x + 1)`

`c) 4x(7x - 3) - 5(3 - 7x) = 4x(7x - 3) + 5(7x - 3) = (4x + 5)(7x - 3)`

`d) x(2x - y) + 4(y - 2x) = x(2x - y) - 4(2x - y) = (x - 4)(2x - y)`

`2B.`

`a) 2x(y - 3) + 5(y - 3) = (2x + 5)(y - 3)`

`b) y(3 + 4x) + 2x(4x + 3) = (2x + y)(4x + 3)`

`c) 2y(3y - 5) - 9(5 - 3y) = 2y(3y - 5) + 9(3y - 5) = (2y + 9)(3y - 5)`

`d) 2y(2x - y) - 6z(y - 2x) = 2y(2x - y) + 6z(2x - y) = (2y + 6z)(2x - y) = 2(y + 3z)(2x - y)`

`3A.`

`a) 3x(x + 4) + 4y(x + 4) + 5(x + 4) = (x + 4)(3x + 4y + 5)`

`b) 5x(2x + 3) + 6x + 9 = 5x(2x + 3) + 3(2x + 3) = (5x + 3)(2x + 3)`

`c) 4x - 16 + 3y(4 - x) = 4(x - 4) - 3y(x - 4) = (4 - 3y)(x - 4)`