6. Calculează: a) (r³ - 2r³ - 1):*; b) (12r + 18r4 - 6x³): (67³); c) (42y³ - 2r³y - 4ry): (2ry): d) (3ry³ - 6ry² - 3y²): (3y²), e) (14x³y² - 7x³y): (7x³y); f) (2xyz + 4x²z - 6xz²): (2xz).

pls pls repede daca imi arata cine imi raspunde ii dau si coroana​