`a) 4x(x - 5) + 6(x - 5)`

`= (x - 5)(4x + 6)`

`b) 10(2x - 3) - x(3 - 2x)`

`= 10(2x - 3) + x(2x - 3)`

`= (2x - 3)(10 + x)`

`c) 6x(x - 4)^2 - 12(4 - x)^2`

`= 6x(x - 4)^2 - 12(x - 4)^2`

`= (x - 4)^2 (6x - 12)`

`d) 8x(x^2 - y^2) - 4x^2 (x - y)`

`= 8x(x - y)(x + y) - 4x^2 (x - y)`

`= (x - y)[8x(x + y) - 4x^2]`

`= (x - y)(8x^2 + 9xy - 4x^2)`

`= (x - y)(4x^2 + 9xy)`