1) (3x - 1/2y).3z - y.(3x - 1/2y)
= (3x - 1/2y)(3z - y)
2) 3y.(x - 2/3) + z.(2/3 - x)
= 3y.(x - 2/3) - z.(x - 2/3)
= (x - 2/3)(3y - z)
3) (x - 5)² - (5 - x).y
= (x - 5)² + (x - 5).y
= (x - 5)(x - 5 + y)
4) (x - 2)(x + 2) - 3y.(x - 2)
= (x - 2)(x - 3y + 2)


